study unit basic metalworking and machine tool operation
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Study Unit
Basic Metalworking andMachine Tool OperationBy
William Schumaker
Copyright © 1998 by Education Direct, Inc.
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Printed in the United States of America
02/14/03
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About the Author
William “Bill” Schumaker was born of Swiss immigrant parents on October 19, 1915, on a
backwoods homestead near Colville, Washington. Elk, deer, bear, pheasants, grouse, rabbits,
and other small game were plentiful in Bill’s youth. No wonder he took an intense early inter-
est in hunting and guns. Bill hand filed his first “gunsmithing” work while in the fifth grade—
a front sight made from a fire-annealed piece of half-round file and a copper penny. Somehow,
this tiny creation still sits in a box somewhere in Bill’s shop despite endless moves, and a
world war!
While in high school, Bill joined the Fort Colville Gun Club. He became small-bore rifle champi-
on within two years. Bill thrived on competition and so he won many events prior to becoming
Washington State Gallery Champion in 1941. In 1942, he set a new national record.
World War II sent Bill through Aircraft mechanics school, but his firearms skills prevailed.
Soon he was armament chief on a squadron of B-17s and B-24s, as well as becoming top
Non-Com of Air Force ground training in small arms at Bradley Field, Connecticut.
After World War II, Bill resumed his civilian rifle competition with a vengeance. He recaptured
the Washington State Championship in 1949, and he won the Idaho State Championship in
1956. Between triumphs he was Inland Empire Aggregate Winner from 1947 through 1949,
high man on Spokane’s winning 1949 Hearst team, and NRA Sectional Champion in 1953
and 1956.
Bill loved the English language from his youth, although he spoke fluent German before learning
English. Bill loved writing also and he sold his first gun-hunting story to GUNS magazine in
1948. He soon began writing the “Gunsmithing Bench” column for Shooting Industry Magazine,
a post he kept for about 25 years. Bill also wrote the “Workshop” column for New York’s Guns
& Game Magazine for about six years. He has authored for Guns & Ammo, Shooting Times,
Gun World, Outdoor Life, and Petersens Hunting. His color photographs have appeared on the
covers of American Rifleman, GUNS, and Guns & Game Magazines, Spokesman-Review Hunting
Edition.
Bill still does gunsmithing work at his near-the-home shop. He still takes photo and writing
assignments, and yes, he still shoots rifle with his local club.
iii
In this study unit, you’ll learn how various
metalworking tools serve the gunsmith.
Some tools are simply prerequisite to gainful
employment in the field and you should
purchase them immediately. A quality drill
press for drill and tap scope work is just one
example. An assortment of hand tools, a grinder, and a good
solid vise are others. Fortunately, most of these basic tools
are relatively inexpensive. Unfortunately, some tools, like a
lathe, milling machine, and welding equipment, are quite
expensive. These too, however, soon become a necessity for
those pursuing specialty gunsmithing.
We approach this unit from a task-oriented perspective. We
stress that those purchasing more advanced metalworking
tools should be sensible enough to obtain proper training in
their use. We cover practical application and safety rather
than basic startup procedures. Those coming to this unit
with an eye to identifying metalworking tools and how they
can generate profit will find themselves well served. Those
who already possess a metalworking background, along
with those who don’t, will learn much from this gunsmithing
legend.
When you complete this study unit, you’ll be able to • Recognize various metalworking tools and identify their uses
• Demonstrate how to fit a gun barrel to an action
• Explain how to open a bolt face in a lathe
• Discuss how to alter military and other bolt handles forscope mounting
• Perform precision sear facing with mini-tool post grinders
• Summarize drill and tap and scope mounting procedures
• Diagnose and correct cartridge feeding problems
• Jewel a bolt
• Build your own glass bead blasting cabinet
• Build your own belt sander
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PROFESSIONAL HAND AND POWER GUNSMITHING TOOLS 1
Introduction 1Fitting New Military Barrels 2Bench Grinders 3Hand Tools around the Benches 4Drilling and Tapping 5
STRAIN-FREE SCOPE MOUNTING 15
Shooting a Scope under Strain 18Scope Alignment Rods Are Helpful 18Scope Centers Vary 19Bolt Jeweling with a Drill Press 23
MILITARY RIFLE BOLT FORGING 20
Longer Bolt Handle Breakthrough 23The Bench Grinder 31Grinder-trimming Forged Bolts 33The Importance of Bench Grinders 34Shop-required Buffing Equipment 35
DIAGNOSING AND CORRECTING CARTRIDGE FEEDING PROBLEMS 39
Whipping Knife-sharp Extractor without Tension 42Emergency Alteration 44Action-rail Tolerances 44Correcting Cartridge Jump-outs 47Influential Magazine Follower Dimensions 47Wrong Feeding Diagnosis on Military Krag Rifle 48
THE LATHE: KING OF GUNSMITHING TOOLS 50
A Barrel Vise 51Gunsmith-built Action Wrench Hammer 52The Complete Shop 53Details of a Barrel Fitting 53Stainless Steel vs Chrome-moly Barrels 59Shop Tips 60
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Contentsvi
BOLT FACE OPENING (MANGUMIZING) IN THE LATHE 62
Precision Sear Facing with Mini-tool Post Grinders 66Drill Rod for Making Parts 68W-1 Water-hardening Drill Rod 69
SHAPING MUZZLES 72
Growing Barrel Muzzels (Sporters/Target) 72How to Crown (Face-off) Shotgun Muzzles 73
ADVANCED GUNSMITHING SKILLS 77
The Palmgren Milling Attachment for the Lathe 77Lathe-making a Tap 79The Milling Machine 81Welding Requirements 83Soft-soldering vs Silver Soldering 86Front Sight Installation 86Parts-holding at the Workbenches 88Joining Two Firing Pins 91
BUILDING YOUR OWN EQUIPMENT 94
Building a Glass Bead Blasting Cabinet 94Plans for a Belt Sander 95
SELF-CHECK ANSWERS 107
EXAMINATION 117
1
PROFESSIONAL HAND ANDPOWER GUNSMITHING TOOLS
Introduction
The old adage that a craftsman is only as good as his or her
tools is especially true of gunsmithing. I remember when I
started out. For several years an ever-prevailing financial
bottleneck prevented me from purchasing adequate equip-
ment and tools. My earning potential suffered as well as my
professional development. For example, although my shop
had a homemade buffer, a medium-value drill press, welding
outfit, and a good eight inch bench grinder, I had to send
rebarreling work to an “equipped” gunsmith, which was both
costly and time-consuming. I felt I conveyed the impression
that I was merely a dealer—not a gunsmith. Initial public
impressions about a new business are difficult to change.
I begin this study unit by conveying an important message to
you, a message you’ll undoubtedly hear from other Gunsmith
authors—if you haven’t heard it already. The message is that
good tools pay for themselves. You can accomplish a lot of
work and make a lot of money using quality hand tools. Then,
if and when needs arise and finances allow, you can add a
quality drill press and a bench grinder to your shop. Also,
those who specialize in metalwork might find that a lathe
and/or milling machine and welding equipment are in order.
There’s no denying that such equipment is expensive. Before
making an investment, carefully evaluate whether the invest-
ment is warranted. On an almost daily basis, gunsmithing
supply houses introduce tools that make task completion
Basic Metalworking and Machine Tool Operation
easier and less expensive. For example, you can order a
semifinished prethreaded barrel and do the final fitting with
relatively inexpensive (compared to a lathe) hand tools. Also,
you may decide to send the action out to a shop that special-
izes in barrel work. Most barrel shops offer dealer discounts,
so you can still make some money for handling such work.
I believe that if you use a tool frequently, it will pay for itself.
I do a lot of metalwork in my shop, and I consider a lathe
and welding equipment to be necessities. Although I have
(and frequently use) a milling machine, we can accomplish
some gunsmithing tasks covered later in this unit with a
Palmgren milling attachment on the lathe. I present this
option in light of avoiding the steep cost of a milling machine.
When I began gunsmithing, I didn’t purchase any expensive
machinery right away. I don’t recommend that you do either.
In fact, you shouldn’t even consider expensive machinery
until you’re properly schooled in its operation and qualified
to evaluate its worth. This way, if and when you do make an
expensive new or used purchase, you’ll be sure to get your
money’s worth.
Warning: Lathes, milling machines, welding equipment, and
hand tools are dangerous in inexperienced hands. In the case
of hand tools, always follow instructions provided for their
proper and safe use and heed manufacturer warnings!
Concerning operating advanced equipment and machinery,
many technical trade schools and community colleges offer
“hands-on” instruction in the proper use of advanced equip-
ment and machinery. Seek these schools out and obtain
proper training before trying to use advanced equipment and
machinery. When I was starting out, because of necessity, I
learned a lot through trial and error. Fortunately, times have
changed. Take advantage of available training.
Fitting New Military Barrels
Early in my gunsmithing career, many customers came to
my shop with surplus 1903 Springfields and 1917 Enfields
that had badly worn and damaged barrels. New ones were
available by the dozen at a modest cost then. Fortunately,
most new military barrels were chambered slightly short. A
Basic Metalworking and Machine Tool Operation2
Basic Metalworking and Machine Tool Operation 3
new .30–06 removable piloted finishing reamer in conjunction
with a heavy Vickerman barrel vise enabled me to handle
this situation, although hand-reaming—which I no longer
advise—was necessary then.
Sometimes, the new barrel chamber was already too deep
(with excessive headspace), or those nuisance Springfield and
Enfield extractor slots and cone-shaped chamber approaches
required altering. Consequently, I had to wrap up a package,
write a letter, and send a check to another gunsmith. I felt
that I was losing profits, time, and reputation. Eventually,
I purchased a lathe.
You’ll never realize how many types of jobs you can do with a
lathe until you learn to operate one. If your shop is in a rural
or small-town area and time allows, you’ll also be making
parts for equipment besides guns. A shop with equipment
attracts and impresses customers and visitors. My point,
again, is that increased business will pay for better and more
equipment.
Bench Grinders
Those who claim you won’t ever need a bench grinder don’t
remember the early military conversion heydays when grind-
ing off big 1917 Enfield ears was an almost daily task. The
work required a heavy-duty, 8 inch wheel grinder to do a
good job, and the grinder has many other uses.
Further into this unit when discussing low bolt forging, I
mention a medium-class grinder fitted with cut-off wheels,
plus a smaller 1/4 hp (horsepower) grinder near the main
workbench. My point is that as business picks up, you can’t
beneficially change grinding wheels on your “one” grinder.
Grinder wheels must be diamond trimmed into balance and
left in that position on their respective machines. I have
instant access to six different wheels. As soon as you can
afford it, you should too. You’ll realize the need even more
if your shop graduates to having a helper.
Hand Tools around the Benches
Files, hammers, wrenches, punches of many types, stocking
chisels, scrapers, knives and endless other items line the
fringes of gun shop workbenches. It’s important that you
keep your tools easily visible and accessible. Wooden clothes-
pins work great for small tools and won’t scar or magnetize
them. Take one half of the clothespin off its spring clamp,
drill small holes in the tapered thin end, and tack it to a ply-
wood back plate on the wall behind the benches. Arrange
their height and spacing according to tools and your taste
(Figure 1).
As you progress, you’ll need a 1 inch and a 2 inch microme-
ter, a depth micrometer, calipers, and endless other tools.
Listing everything I can think of is useless because you
Basic Metalworking and Machine Tool Operation4
FIGURE 1—Shown is mysimple, low-cost, minimum-effort wall toolholder. Itreated the back sides ofthe wooden clothes pinswith 3 minute epoxy to holdthe pins in place. With thisarrangement, dozens oftools are within sight andinstant reach.
Basic Metalworking and Machine Tool Operation 5
already have the Brownell’s gunsmithing supply catalog.
Common sense and logic dictate a good starting lineup.
You should acquire more tools as the need arises.
Drilling and Tapping
Most gunsmiths have probably spent more time drilling and
tapping and installing scope mounts and sight bases than
they’ve devoted to all other in-shop activities. This was espe-
cially true directly after World War II when countless military
rifles were transferred to civilian ownership. While the big
rush is over, new supplies of old military rifles keep coming;
hence, the importance of becoming adept at drilling and
tapping (Figure 2).
Many barrels are hard and extremely difficult to work with
despite the latest super-hard drills and better taps. Although
we can drill almost anything, cutting a thread in the drilled
holes is still a leading troublemaker.
Before hole location action jigs were available, it was com-
mon to use a parallel-jawed caliper to square the scope base
on the action top relative to the underside of the action flat.
Then a gunsmith would use a thin, hard scribe to reach
through the screw attaching holes to scribe the hole position.
FIGURE 1—Shown is my FIG-URE 2—You can sharpen dulltaps with a small emery stonein a Dremel tool post grinder.
Next the gunsmith would center-punch and drill the holes
one at a time. Often it was merely a “try-to-drill-the-hole”
effort unless you used some hard drills available through
gunsmiths’ supply houses. Unfortunately, super-hard (car-
bide) drills break easily—especially as they go through the
action.
The easiest and best thing to do is to purchase #31 “hard”
drills, along with the best taps available. A three-flute carbon
tap has narrow cutting lands. It won’t endure as much cut-
ting torque as a two-flute high-speed steel tap. However, if
you ever break a two-flute high-speed tap in a hole, you’ve
had it! Or more aptly, it has you! Unless you have room to
reposition the hole, the only out is sending the barreled
action to a shop equipped with an ultramodern electric
discharge machine (EDM), which can actually burn it out,
yet save the thread. This is why many gunsmiths went to
carbon, three-flute taps. If broken, you can shatter and
chip them out of the hole—sometimes!
Depending on how tight the tap is at breakage, the three-
prong tap removal tools sometimes work. Due to the extra
thread-lands surface of the two-flute taps, the removal tool
can seldom move them, which emphasizes the need to han-
dle small 6–48 taps delicately. Use tapping compounds/oils
liberally, such as Do-Drill and others. Start the thread with a
new taper tap. If it’s a bottomed hole, grind off the dead point
tip of the tap to lengthen the reach. The original grind of
some taper taps prohibits use in a bottomed hole.
Alternate Taps
Every tap is slightly different. After you easily turn one tap
into a hole as far as your skilled hands safely determine,
carefully remove it. Take another tap to try threading deeper,
or slightly enlarge the thread. I never throw away a tap until
it’s down to a mere stub. Keep grinding away the worn front
end and relieve the lands’ heel clearance a bit on a grit-coat-
ed buffing wheel. I’ve worked many a satisfactory thread into
a hard, tight hole by using the alternate-taps system. You
must develop a genuine, tender-yet-firm feel for safe tapping.
Experience teaches you how much pressure you can apply
on your tap wrench for a given tap, hole, and situation.
Basic Metalworking and Machine Tool Operation6
Basic Metalworking and Machine Tool Operation 7
Anneal Hole Area
Annealing (softening metal) the spot to be drilled makes
tapping much easier. When working with different actions,
steels, and heat treatments, annealing is difficult. Inexpe-
rienced gunsmiths have probably “hardened” more actions
than they’ve annealed, which creates danger.
Warning: Never apply heat to an entire unshielded receiver
ring area! Preferably, remove military barrels from actions
before annealing, drilling, and tapping.
Removing barrels from actions takes longer only theoretically!
With the barrel out, you can drill all the way through the
front of the action. It’s much easier to tap. You can deburr the
hole(s) on the inside breakthrough area, saving tap chipping.
In the event you drill a hole with a super-tough professional
drill, you can anneal it after drilling (and much more evenly).
Furthermore, in the event a carbon tap gets broken in a
through-hold, it’s easier to punch it through, shatter, or pick
it out. You should apply heat with a medium-small acetylene
torch tip to the hole or receiver spot, protected with wet
asbestos around outside extremities. Prior to applying torch
heat, you should polish the metal surface white. Watch the
metal color slowly draw to blue, hold briefly with retracted
flame tip, retract more, and allow the steel to cool slowly.
Warning: Removing all heat immediately, and letting the
steel cool rapidly via the mass of adjoining metal usually
hardens it, causing both danger and more troubles.
Grinding Drilling Location Spots
Whether you use a parallel clamp, calipers, or an elaborate
drilling jig, rescribing, concave spot grinding, and rescribing
several times as you progressively grind is probably most
important to accurate hole location and drilling. If the action
steel will take center-punch, this (added to the concave spot-
ting) does no harm. However, it’s usually not helpful, as
drills follow concave grinding spots nicely.
Using a Scope-mounting Jig
For scope mounting, the B-Square Professional Scope-
mounting Jig is available with complete directions (Figure 3).
Its flat base block, bore align arbor, V-bushings, drill bush-
ing, and jig bars for different actions assure you of perfect
top-of-the-actions holes positioning (Figure 4). It’s still to
your advantage to scribe the hole locations through the drill
bushing, remove the jig, and then concave grind the tiny drill
spot locations (Figures 5 and 6).
Basic Metalworking and Machine Tool Operation8
FIGURE 3—Drilling MauserM-98 with B-Square Scope-mounting Jig and Drill Bushing
Basic Metalworking and Machine Tool Operation 9
FIGURE 4—A hardened drillbushing guides the drill andensures correct hole location.
FIGURE 5—After light center-punching through the drill jig,use an electric grinder with ainch emery stone to concavethe drill-starting spots. Afterrepositioning in the jig, re-center-punch through the jig’sdrill guide. Make a centerpunch from a broken carbidedrill for perfect alignmentthrough the drill guide. Thepunch can be accuratelypointed using your small toolpost grinder in a lathe.Center-punching through thedrill bushing provides perfectcentering.
Note: Starting a drill perfectly is important. You can make a
small effective center punch from a broken super-hard #31
drill.
More on Annealing
Another popular method for annealing is to use a steel block
or rod approximately 1 inch in diameter � 2 inches long.
Contour the end of the steel to contact hole areas of the
receiver. Heat the steel piece red-hot. Place it against the
receiver contacting the holes area and allow it to cool com-
pletely. This offers slightly better heat control. Cooling slowly
should condition the steel to drill and tap.
Note: Concerning drilling and tapping, one line of thought is
that if the metal is too hard to drill, it’s certainly too hard to
tap. If you can drill without hardened drills using only con-
ventional screw machine short drills, which also wander less,
then you can be reasonably sure you can also tap the metal.
There’s much truth to the saying that carbide drills just pre-
pare a hole in which you break your tap.
Basic Metalworking and Machine Tool Operation10
FIGURE 6—Sides of 1 1/4inch V-blocks provide an idealbase surface for the bottomflat of the Mauser and otherrifle actions. Slight shimmingin the drill press compoundvise allows tightening foraccurate drilling (Brownell’shard-coated #31 drill).
Basic Metalworking and Machine Tool Operation 11
Standardizing Hole Spacing
There’s been an increased availability of military Mauser
rifles, and some Springfields and Enfields have been finding
their way back home. Consequently, most new gunsmiths
will discover that drilling and tapping such rifles is still a test
of gunsmithing skill. One still-unsolved problem is the various
scope base hole spacing used by different manufacturers.
Makers of quality adjustable scope mounts such as Redfield
and Beuhler give their bases a recoil lip that butts against
the rear of the receiver ring. Weaver and the lower-cost
imports lack a recoil lip and are installed at various fore and
aft positions. Inaccurate hole drilling and the fact that scopes
don’t all have perfect optical centers quite often make it
impossible to zero in a scope after it’s mounted.
You could adjust elevation with shimming, but left-right
(windage) remains fixed by the mounting screw holes’ loca-
tions (if there’s insufficient windage adjustment in the scope).
Therefore, military actions drilled for the nonstandard plain
aluminum bases by various gunsmiths wouldn’t accept a
substitute adjustable base. Factory rifles, on the other hand,
had drillings matched by the mount manufacturers. If non-
adjustable bases prevented a scope from being zeroed,
switching to an adjustable mount was easy! At the height of
scope mounting work in my shop, we ran into this situation
up to seven times annually.
When a customer insisted on the low-budget nonadjustable
scope, the gunsmith solved the problem by using an
adjustable base as a template. Then, if the need arose, it was
still possible to install the adjustable base.
Another trick often used on super-hard Enfield actions made
by Eddystone was to enlarge the hole made by the #31 drill
by running a #30 drill into it. This often made tapping possi-
ble without danger of stripping in that super-hard action.
Hand Tapping
Handheld tap wrenches and the chucked tap, even though
it’s a taper-tap, don’t always start in perfect alignment with
the hole. This can make an imperfect hole beginning, and in
shallow holes it could strip.
B-Square’s Tru-Tapper is a small secondary chuck with a
free vertical movement mandrel and T-handles for hand
working (Figure 7).
After drilling the hole, you must lower the drill press table
enough to remove the drill from the press and chuck up the
Tru-Tapper shank. Then, you realign the table. Use a new
and sharp, well-lubed taper-tap, and turn the Tru-Tapper
carefully with its T-handles, using slight downward feed-in
pressure to start the thread cut. After the tap is nicely start-
ed (straight), I prefer to take the action to the bench vise and
use my small, hand-operated tap wrench to finish the thread
(Figure 8).
Basic Metalworking and Machine Tool Operation12
FIGURE 7—The Tru-Tappergives positive in-line hole tapping. The jig keeps theaction level and in line.
Basic Metalworking and Machine Tool Operation 13
FIGURE 8—Hand-Tapping theFront Scope Base Hole
Basic Metalworking and Machine Tool Operation14
Self-Check 1
At the end of each section of Basic Metalwork and Machine Tool Operation, you’ll be asked to pause and check your understanding of what you have just read by completing a “Self-Check” exercise. Answering these questions will help you review what you’ve studied so far. Please complete Self-Check 1 now.
Indicate whether the following statements are True or False.
_____ 1. Super-hard carbon drills are tough to break.
_____ 2. You should never apply heat to an unshielded receiver ring area.
_____ 3. You should never start a thread with a new taper tap.
_____ 4. A three-flute carbon tap has narrow cutting lands and won’t endure as much cuttingtorque as a three-flute high-speed steel tap.
_____ 5. Annealing the spot to be drilled will make tapping much easier.
Check your answers with those on page 107.
Basic Metalworking and Machine Tool Operation 15
STRAIN-FREE SCOPE MOUNTING
Besides drilling and tapping for scope sight mounting, fixing
installations done by the customer on predrilled and tapped
factory rifles undoubtedly surpasses in frequency all other
facets of gunsmithing and gun work. Customers will bring
in a multitude of errors, mistakes, and “done-it-wrong” work
for you to correct. That’s where gunsmithing instructions,
training, and experience pay off.
Note: Prospective gunsmiths must learn to read, understand,
and practice all manufacturer’s instructions. Additionally,
gunsmiths must keep abreast of the latest developments and
never close their minds to further learning!
Before we get into the evils of scope strain within the mount
system, we need to first address the need for perfect rings-to-
scope fitting. You must follow the instructions with Buehler
scope mount rings. The majority of home install-it-yourself
hobbyists somehow fail to either read or follow them. If you
can read, study, and follow instructions, you’ll get substantial
work.
The first problem is that the so-called 1 inch diameter scope
bodies are seldom a true inch. You’ll discover this if you use
your micrometer on them from beginning to end. The high-
quality adjustable Buehler rings are machined and polished
in place for perfect fit. Their laminated shim pack peels off in
sections as required to bring the “into-the-front-base” ring
spud opening to a mating match with the bottom ring spud.
The diameter split and cross-screw are tensioned “tight” to
finalize a perfect fit.
Now we can proceed in obtaining a strain-free position for
your telescope sight. The Buehler mount (as does the
Redfield) employs a left and right opposing windage screw
system. The first big mistake many hobbyists make is leaving
the left windage screw in position at the mount rear as they
bring the ringed scope swing up to it. They presume in-bar-
rel-line, but careful observation reveals that swinging the
scope up to the left windage screw won’t positively position it
there. The scope is under some tension and recoils lightly to
the right. Far too many scope installers simply bring that
right windage screw into position and then force the rear
scope ring up against the left windage screw (under tension),
without worrying about it.
However, that’s the wrong way to do it! The left windage
screw should have been removed, as well as the right. When
swinging the ringed scope into barrel line under slight ten-
sion, move it slightly past center left and right, and with
increasingly shorter left-right movements, work out any left-
right tension (strain). Next, note if the bottom of the rear
scope ring easily bears onto the top of the rear scope base
between the windage screws. If it does, you’ve got it made.
Your scope is strain-free from front to rear rings. Turn in the
left and right windage screws to the relaxed centered rear
ring base, firm them up, bore-sight, and zero in on the range.
Note: Never rely on bore-sighting fixtures for a final zero.
If you have to push the rear scope ring and scope downward
(or upward) to contact the top of the scope mounting base
between the windage screws, you have damaging-to-zero
scope strain.
Scope strain isn’t always easy to work out. Often you can
have a strain-free scope pointing so far out of line with the
bore center that sighting in is impossible with the existing
internal scope adjustments. This calls for steel shims, often
ground to a taper, to laboriously bring the scope mounting
bases and rings into strain-free alignment.
Strain-free alignment might matter little to the average deer
hunter or plinker, but it’s a super item for target, silhouette,
and bench rest shooters, and most long-range varmint shoot-
ers are precisionists plus! “Scope strain” has become univer-
sally recognized by bench rest (BR) gunsmiths. So much so
that they work a 1 inch steel bar treated with lapping grit
back, forth, and around with a wrench to progressively tight-
en the rings as they lap until total inside contact is achieved.
Split steel rings respond best.
Note: It’s wise to get elevation alignment as close as possible
before doing the final lapping to bring the scope into a
relaxed position (from which it’s least likely to change).
Basic Metalworking and Machine Tool Operation16
Basic Metalworking and Machine Tool Operation 17
Shooting a Scope under Strain
Scope body metals forcibly held in a bind (strain) can do
strange things. Some gradually shift hither and yon, but
most yearn to relax their way out of the position they were
forced into. Like an archery bow left strung for long periods
of time, a scope under strain eventually responds to most of
the force that overwhelms it, in this case strong scope rings
and mount bases. However, the process takes time. Response
may not be complete for years, and the shooter will suffer
accordingly throughout this period. Knowledge and good
gunsmithing can prevent such problems.
Scope Alignment Rods Are Helpful
Professionally made scope alignment rods consist of two alu-
minum rods that are pointed 60 degrees, 41/4 inches long,
and either 1 inch or 30 millimeters in diameter. After
installing a scope base on a rifle action, you should mount
the rods in the scope rings, points facing each other. If every-
thing is in line and you can bring the points to touch, the
scope taking their place in the rings is probably not under
any strain. If the alignment rod points can’t be perfectly
touch matched, some careful work remains.
The most common cause of mismatching rods is variation in
rifle actions, especially military types. Inaccurate drilling-tap-
ping work also causes problems. Front and rear scope bases
and/or one-piece scope bases must not only be level but
basically level with the axis of the rifle bore to a degree easily
adjusted with the scope’s internal adjustments.
Quality mounts have provisions for windage (left and right)
adjustment, which makes it easy to line up the alignment
rod points windage-wise. The big culprit can be elevation. In
Figure 9, the right rod point (at the arrow) is visibly higher
than the rod point mounted in the rear scope ring.
A scope installed in rings as pictured in Figure 9 would place
an undesirable bend and strain onto the scope body. The
strain affects accuracy, zero holding, and possibly the internal
optical system.
The easiest way out is to shape a steel shim the approximate
thickness of the elevation shortfall. The only other answer is
to contour-mill the underside of the front scope base.
The top overall surface length of the two rods should also be
level, as it’s possible for the points to touch without the rods’
bodies being in line. It’s touchy work that requires a good eye
and hands, plus know-how, understanding, and judgment.
There will be times when the basic height of the bases will be
level. Still, the front or rear of either the front or back base
can be pointing slightly down or up. Carefully tapered shims
will be required.
Note: To this point, we’re assuming the barrel in the action is
straight and/or not an ultralight model with heavy stock
upward or other directional tension that can actually change
barrel point zeroing. You can witness the effect of barrel
pressure by placing a barrel blank heavy chamber end into a
three-jaw lather chuck and locking it up firmly. Then, with a
bit blank in place, move the lathe carriage and toolpost just
Basic Metalworking and Machine Tool Operation18
FIGURE 9—The front scopemount’s alignment rod pointis higher than the rear ringrod point. The rear scopebase must be shimmed “up”to level. Windage adjustmentin the rings accommodatesleft-right movement.
Basic Metalworking and Machine Tool Operation 19
touching the barrel muzzle or any other part. Back off the
crossfeed a given number of thousandths and then advance
enough to take up the slack. This puts you in position to
measure the actual amount of spring-out from its natural
position that a mere light or medium finger pressure can
exert.
Now, think about force-locking up a scope in misaligned
rings and/or bases, and realize the force being exerted by
the powerful leverage of screws. The slightest deviation
from a relaxed central position for a scope can cause serious
troubles. I made my scope alignment rods from round plastic
stock. It took less than 30 minutes. Though not a cure-all,
they help in diagnosing trouble-causing scope strains.
Scope Centers Vary
You should be aware that scope centers coming from the fac-
tory aren’t identical. Suppose a scope, mounted with a
Weaver-type, nonadjustable mount, just happened to be so
close that a few clicks of windage and elevation centered bul-
let impact point on the target. Then the second, fourth, or
tenth such identical scope will usually shoot elsewhere when
installed in the same mount on the same firearm in a strain-
free installation. Variation will be even greater if the scope is
held in the rings under strain.
During the post-World War II “scope boom,” even small deal-
ers ordered scopes by the dozens. One midwinter lull-season
customer wanted his 2 1/2 power scope in a nonadjustable
mount replaced with a better-class, higher-powered glass. He
hoped a new mount wouldn’t be necessary. Having about 10
scopes of the type sought in stock, I conducted the following
experiment. I mounted each scope in his rings and carefully
bore-sighted it on his rifle, making notations on each. They
varied from an almost impossible 1 1/2 feet in windage at
50 yards to less than 2 inches. Similar vertical differences
existed.
I went back to the closest one, pleased the customer, and
chalked up the experience to “learning.” This experience also
proved that some scopes could be under strain in the identical
mount that left others relaxed. Hence, we can’t overemphasize
the importance of individual fitting.
Bolt Jeweling with a Drill Press
Jeweling or damascening is an ancient form of decorating
metal. It has a series of overlapping, highly polished circular
spots, usually holding the overlap just short of the swirl
centers, which loom out as jewels in the lengthwise rows.
On firearms, you usually find jeweling applied to rifle bolts,
cartridge followers, ejector housings, and the flats of bolt
handles.
In jeweling, the bolt body may be coated with abrasive com-
pound and the “whirls” made with a special flexible wire
brush. Or, a dry grit-impregnated rubber tip is held in the
drill press chuck jeweling fixture, which must be sufficient
length to clear the bolt handle. No grit compound is used
with the dry self-impregnated rubber tips.
The wire brush system of jeweling is more popular, as after
slight wear, it conforms more closely to the bolt’s contour
and is more attractive (Figure 10). The special wire brushes
have a tendency to flare when the necessary slight contact
working pressure is applied. Special tiny “O” rings, shrink
tubing, and even a shallow nylon thread wrapping around
and next to the mandrel hold the steel bristles at uniform
round diameter. With the drill press running at high speed,
the operator raises and lowers the jeweling tip slightly to
allow the brush surface to swell out and contract slightly.
Fine jeweling with wire brushes depends on the base polish,
your manipulation of the drill press, and fixture indexing.
This is where the value of a compound table shows up. The
table enables you to move your spots progression uniformly
(Figure 11).
Otherwise, you can use a “fence” clamped to the press table
and manually moved for spots locations. Or, you can go the
expensive route and purchase an elaborate fixture wherein
the indexed adjustments are incorporated. As with other
gunsmithing, there’s room to experiment: with jeweling
you use grits, fixtures, and tips. When you’ve finished a job,
thoroughly wash and rinse all jeweled surfaces in cleaning
solvent and air-blow dry inside and out. Then wipe with a
quality light oil.
Basic Metalworking and Machine Tool Operation20
Basic Metalworking and Machine Tool Operation 21
FIGURE 10—This photographdepicts jeweling with a wirebrush tip.
FIGURE 11—A compound drillpress table gives accuratespacing with a B-Square jew-eling jig. The brush tip in thephoto is thread-wrapped foruniform medium “swirls.”
Basic Metalworking and Machine Tool Operation22
Self-Check 2
Fill in the blanks in the following statements.
1. The special wire brushes used in jeweling have a tendency to _______ when the necessary slight contact working pressure is applied.
2. Buehler scope mount rings are adjustable via their laminated _______.
3. The _______ method is the most popular type of jeweling.
4. You can’t rely on _______ fixtures for establishing a final zero.
5. Adjustable scope mounts have windage screws that provide adjustment to the _______and _______.
Check your answers with those on page 107.
Basic Metalworking and Machine Tool Operation 23
MILITARY RIFLE BOLT FORGING
Altering Mauser, Springfield, and M-54 Winchester bolts
via forging (not welding) isn’t just a matter of turning on
an acetylene torch, heating the bolt, and pounding it down.
That theory has practically ruined thousands of perfect bolts.
Forging (forming metal by heating and hammering) a bolt
properly isn’t easily learned—especially without proper
instruction. Involved with bolt forging from its beginning,
I had to learn by my mistakes; however, in a way I was
fortunate. Experience taught me to correct the mistakes.
Shortly after World War II, I obtained my first set of forging
blocks. I had found it impossible to turn out an acceptable
job by taking my bolts and blocks to the nearest welding
shop and attempting to coach people on heat application.
The forging service I used was far from perfect. The bolts
were pounded down too much, which led to too short a bolt
handle. Sometimes the bolt handle shank base was still too
high to give an adequate clearance for low scope rings and
large scopes.
Longer Bolt Handle Breakthrough
No one seemed to have the answer. The best known gun-
smiths in the nation were sawing off the military bolts and
skillfully welding on knurled and fancy handles and knobs.
Many others clumsily welded on replacements (some only
surface welded) that broke off in the field, causing hunters
to lose game.
My bolt forging efforts were acceptable but still produced bolt
shanks a little shorter than desired. One day, a “mechanical
bell” went off in my brain. Why did I so often get a nicer bolt
forging job from the Mauser straight-handled bolts? There
had to be a mechanical reason. Months of brain scratching
climaxed one night about 3 A.M. when I awoke with a possi-
ble solution! It was so clear, I grabbed a pencil and pad and
made notes for some time. I couldn’t sleep until going to the
shop and trying my idea!
It was simple logic: you don’t pound it down, or forge it
down! The straight bolt handles were vertical as held in the
forging blocks. This made it impossible to pound downward
after the handle was heated dull-red for forging. Therefore,
I forged over and outward, not downward. This was why I
was getting a longer, nicer forged bolt on the straight-han-
dled Mausers. After all, when forging metal, you move it in
the desired direction and in desired proportion. My first effort
turned out better than ever (Figures 12 and 13).
Elated with success, I forged a second bolt, determined I
could move whatever portion of that square-like rectangular
Mauser bolt shank base I wanted to transfer out into addi-
tional bolt handle length. Short length was one of the critical
complaints about average forging when compared to welding
new handles on.
Therefore, why should a bolt handle have superfluous verti-
cal bolt body before going into the outward shank takeoff?
The answer is it’s unnecessary. With the bolt in the forging
blocks held in a heavy steel bench vise, insert the steel bolt
plug to act as a heat sink and prevent collapse or distortion of
the bolt body. Pack any protruding part of the bolt body with
wet asbestos. With a medium-large tip in the acetylene torch,
heat the bolt handle to red-forging temperature (Figure 14).
Basic Metalworking and Machine Tool Operation24
FIGURE 12—Don’t pound the handle down. Shown is a pitifully short, high-based,thin-shanked, nearlydestroyed Mauser M-98bolt—pounded down, notforged.
Basic Metalworking and Machine Tool Operation 25
FIGURE 13—The straightshank Mauser bolt, left,is eas-ier for beginners to forge thanstandard Mauser (center) andthe U.S. 1903 Springfield bolt(right). All will forge nicely.
FIGURE 14—Shown is a red-hot bolt that’s acetylenetorch-heated at the bend.Acustom form-fitting wrenchlifts the bolt to vertical position.
Warning: Asbestos can be dangerous to your health. You may
prefer to use Brownell’s Heat Stop heat-control paste as a
replacement for asbestos. Heat Stop keeps heat from spread-
ing when welding, soldering, or brazing, and it’s a very good
substitute for asbestos. Also, some gunsmiths who only
infrequently need to control the spread of heat simply use
wet rags to stop it. In this procedure, an assistant repeatedly
pours water onto the rags to keep them wet and cool. As a
result, the rags don’t heat up and ignite from the torch heat,
and the covered metal surface remains relatively cool.
Continuing, I took an 8 ounce ball peen forging hammer and
flexed it in my working arm, ready for fast work. I pounced
on the upper 50 percent of the rectangular Mauser bolt
shank base rapidly with the medium-heavy forging arm and
evaluated the progress. I made sure to apply as much heat
underneath as on top (Figure 15).
Speed is the key to much of your success. Keep the bolt
working, forging, and red-hot. You’ll learn the exact color
from experience. Use the flat side of your ball peen hammer
until the bolt handle leans heavily away from you (Figure 16).
Basic Metalworking and Machine Tool Operation26
FIGURE 15—This bolt is stillheated red in forging blocks;asbestos-packed, heat sinkinside, the handle is nearlyvertical and ready to forge.Remove the wrench, grab theforging hammer, start fast,and work 50 percent downinto the rectangular base.
Basic Metalworking and Machine Tool Operation 27
Shift to the ball end of hammer and continue to hammer
forward, away from you more than down, working the steel
outward into a longer bolt shank. Keeping the forging tem-
perature perfect and working fast with rapid semi-heavy
hammering will prevent parting of the metal and preclude
any welding fill-in. (Figure 17).
FIGURE 16—We remove thebolt from the blocks for thisphoto to show precisely thelow forging impact area andhammer angle, initially forcingmetal out and away, NOTDOWN! Naturally, you useforging blocks and vises.
FIGURE 17—After forcing the bolt shank to about 45degrees, switch to the ballend, still hammering awayfrom you, at the angle shown,but adding downward force.
Caution: Never resort to a heavier hammer. Excessive-weight
blows can cave in the bolt body under the bolt handle.
Practice and experience will enable you to visually determine
when the shaping is complete (Figure 18). You can do slight
up or down alteration later. You’ll have flare-out of metal
both under the bolt shank next to bolt body and on top of
the bolt shank, near the bolt body. If you performed the forg-
ing properly, you’ll have more than adequate steel to provide
you with required trim-out. If not, practice more.
Upon completing the forging and shaping, retract the torch
flame gradually to protect bolt temper. There should be no
cocking cam edge, melt-ins, or cave-ins, which are common
to welding on new bolt handles (Figure 19).
Basic Metalworking and Machine Tool Operation28
FIGURE 18—We have the boltout of the blocks to show theDOWNWARD blows and thecenter of the ball in relation-ship to the remaining verticalbase, which is important. It’swithin a few blows of being finished.
Basic Metalworking and Machine Tool Operation 29
If perchance hesitancy and heating circumstances lead to a
soft cocking cam that’s easily cut with a file, no problem.
Return the bolt to forging blocks without the heat-sink cen-
ter. With a wet asbestos plug partway down the bolt body
opening, apply acetylene flame to the cam area until dull-red,
and instantly apply a pack of sloppy-wet asbestos. The cam
area will now be hard enough to resist cutting with a file,
and the temper change won’t extend into undesirable areas.
A properly forged bolt, held in forging blocks and packed
with wet asbestos, with heat-sink installed, won’t allow heat
transmission coloring to extend even into the edges of the
forging blocks (Figure 20).
FIGURE 19—Shown are 1903-A3 Springfield bolts; on theleft, the original; on the right,one completely low-forged andready to trim out and polish.Springfield bolts have moremetal bulk at the shank baseand require more heat and vig-orous forging.
If you or a customer desires a spoon-bill, knurled, checkered,
or other fancy bolt handle, you can safely forge the original.
Then, cut off the original bolt knob two-thirds the distance
out from the bolt body and weld on your new version. In fact,
the cutoff can be anywhere, but leave room to totally heat-
protect the bolt body (Figure 21).
Note: Remember today’s litigious climate; you can’t be too
careful! Use eye, ear, and lawsuit protection! Work carefully!
Basic Metalworking and Machine Tool Operation30
FIGURE 20—Almost all of the original vertical rectangular bolt shank base was converted to length in this forg-ing job. Note that the proof mark and base outline are still intact. You can learn to do likewise. You’ll amaze yourcompetitors and gain their respect.
Basic Metalworking and Machine Tool Operation 31
The Bench Grinder
Bench grinders are a blessing in modern work areas.
Gunsmiths who can afford them use at least three because
they’re timesaving. One general-purpose, heavy-duty bench
grinder handles everything from Enfield. Another smaller
one, close to the workbenches, is capable of a multitude of
light trimming, shaping, sharpening, etc. The third is equipped
with a cutoff wheel about 5/32 inch face width, the other
wheel around 1/16 inch face. Circumference size may vary
according to your grinders (Figure 22).
Note: It’s 100% impractical to change grinding wheels for
various operations. To run and cut properly, grinding wheels
must be trued (a big job quite often requiring diamond trim-
mers). Removing and reattaching them changes everything.
Warning: Always use safety goggles and a respirator when
working with bench grinders and other equipment that emits
dust, grit, chips, etc.
FIGURE 21—Shown is thelonger, completely trimmed-out,bead-blasted Mauser bolt, with-out welding, pits, breaks, ortemper loss.
In an active shop, grinders, the lathe, drill press, and all little
bench tools are almost always in constant use. When you go
back to trimming out that newly forged bolt, mechanically
inclined gunsmiths can see the flare-outs and forge-overs
that should be ground off. The cutoff wheel on a grinder
enables you to work on the underside of the bolt shank,
where larger wheels can’t reach (Figure 23).
Basic Metalworking and Machine Tool Operation32
FIGURE 22—Shown is thereceiver bridge grinder spottedfor scope mount holes drilling.A bench grinder with a inchcutoff wheel is ideal to rough-notch a rifle action for a newlyforged low bolt. Use inchdiameter emery tips for accu-rate notch finishing. Theassembled bolt must haveslight up-and-down clearancewith the safety on.
FIGURE 23—This inch facecutoff wheel enables gun-smiths to reach into touchyareas for bolt-forged metal flare removal.
Basic Metalworking and Machine Tool Operation 33
Bench grinders with the wheels from 3/4 inch to 1 inch face
width are also indispensable. You can use them for dainty or
heavy work. No shop can be without them. Keep a smaller1/4 horsepower grinder within arm’s length of your main
workbench. You’ll need it often.
Once you learn to forge correctly, a longer new bolt forging
takes less time than it takes your competitor merely to saw
off the bolt handle. Also, there’s as much cleanup time
required on a welded bolt as there is on a forged bolt. After
all the rough shaping, switch to hand work and buffing
wheels for the final master’s touch.
Grinder-trimming Forged Bolts
With major shifting of metal during bolt forging, you can
expect flare-outs, overhangs, and often some need for thin-
ning, shaping, and smoothing. In such cases you would use
bench grinders with wheel faces of 1/8, 3/4, and 1 inch. A
1/16 inch cutoff wheel to go with your 1/8 inch wheel is often
handy. Frequently, a slight “bellying” of surplus metal occurs
on the underside of the bolt shank, outward from the bolt
body. You can remove surplus metal most easily with the1/16 inch and 1/8 inch face cutoff wheels, as they can reach
into the area. The 1/8 inch cutoff wheel does a good job of
removing the side-flare on either side of the top area where
the forging blows were struck. You can easily trim the top
flat of the forged bolt handle with the larger bench grinder
wheels up to 1 inch (Figure 24).
Next, finish the surface on 1 inch face, felt buffing wheels,
initially treated with #150 grit. Then, use the finer #450
and move on to sailcloth buffing wheels with #450 or finer
polishing compounds and rouge for the final polish. This
also provides better retention of lubricants and antirust
preparations.The Importance of Bench Grinders
The Importance of Bench Grinders
As is evident from reading the first few pages in this unit,
bench grinders are turned on and off more than any other
general shop equipment. As you can afford them, acquire
at least three so that you can keep the wheels trimmed and
balanced, and so that you won’t lose time in making wheel
changes (Figure 25).
The most casual firearm repair often requires a touch on
a grinder. Welded parts have to be trimmed, dimensioned,
and faced off. New gun parts need to be mated to remaining
working mechanisms. Keep a small or medium 3/4 inch
wheel-face grinder within a few arm lengths of your main
workbench. One wheel should be fine grit and the other
medium or coarse, or arrange in accordance with your shop’s
most common demands.
Basic Metalworking and Machine Tool Operation34
FIGURE 24—You can use alarger 1 inch face emery wheelto grind flat on top of forgedbolts or for a multitude of otherheavier-duty shop uses.
Basic Metalworking and Machine Tool Operation 35
Shop-required Buffing Equipment
Basically, you use buffing equipment to prepare steel sur-
faces on guns and gun parts for bluing. Buffers have grit-
treated wheels of solid felt, 1 inch wide, 6 to 8 inches in
diameter, and loose and stitched muslin wheels. They have
almost daily and hourly additional uses (Figure 26).
After an approximate grind-down of a welded repair, felt
#150-grit and #240-grit wheels offer an ideal and much
smoother finish with a surprising contouring capability.
You can finish lathe bits and chisels for stocking work and
other uses on the buffing wheels. Fine-cut chisels respond to
a delicate application of buffing wheels with grits of #450–500
and down to rouge, provided you learn how to hold them for
proper angle and tension. Sharp tools save time and make
work more enjoyable.
FIGURE 25—Here BillSchumaker gives a final touch-up to a bolt handle. Easyaccess to hand and other toolssaves time in this “U”-shapedwork area.
Figure 27 shows a buffing machine shop arrangement for you
to consider. The shop has the window for light, compressor
in the right corner, a blasting cabinet to the right of the com-
pressor (not shown), and a central stand within easy reach
for parts.
Basic Metalworking and Machine Tool Operation36
FIGURE 26—Shown is a home-shop welded buffer frame, con-sisting of pipe, eye-beam, andbar stock. Except for one bear-ing replacement, this setup hasbeen in service since the endof World War II. The standingdisc (right side) is a handyaccessory for woodworking andrecoil pad trimming.
FIGURE 27—A Typical BuffingMachine Shop
Basic Metalworking and Machine Tool Operation 37
Buffing barrels and barreled actions require “swing-room,”
especially when getting to the smaller parts. The point isn’t
that you use the buffer that much, but rather that you have
the various grit-size wheels in place when you need them.
Then you can swing from one wheel to the next without
changing and rebalancing. In the progressive shop, many
wheels are in position at once. Going from one to the next is
routine and without delay and problems (Figure 28).
FIGURE 28—This recommendedBaldor buffing machine givesadequate wheel clearance. Ithas an 8 inch diameter 1 inchface felt wheel on the left (sewn sailcloth) and a finalrouge polish wheel on the right.
Basic Metalworking and Machine Tool Operation38
Self-Check 3
Indicate whether each of the following statements are True or False.
_____ 1. Upon completing forging/shaping, you should retract the torch flame immediately toprotect the bolt temper.
_____ 2. You can use bench grinders with the wheels from inch to 1 inch face width fordainty or heavy work.
_____ 3. Altering bolts is just a matter of turning on an acetylene torch, heating the bolt,and so-called “pounding it down.”
_____ 4. When forging metal, you should move it in the desired direction and in desired proportion.
_____ 5. To run and cut properly, grinding wheels must be trued, a big job often done withdiamond trimmers.
Check your answers with those on page 107.
Basic Metalworking and Machine Tool Operation 39
DIAGNOSING AND CORRECTINGCARTRIDGE FEEDING PROBLEMS
Gunsmithing is a highly technical trade, and no one aspect
of it takes precedence over another. The safety factor and
correct chambering and headspacing during barreling are
very significant, as is proper function. Earlier study units
stressed that no matter how great the firearm might look,
if it fails to function correctly (unless it’s a collector item)
it’s probably worthless.
Cartridge feeding problems are a major cause of firearm
malfunction. Factory arms aren’t immune to cartridge feeding
problems, but the biggest headaches arise from military
conversions. Problems arise when actions designed for one
size military cartridge are forced to accept modified case
shapes and bullet diameters. I’ve been performing military
conversions since the end of World War II and I’ve spent
years diagnosing various problems. The following information
should help those who try their hands at military conversions.
Mauser 8 mm and 7 mm cartridge cases have slightly less
diameter at the front shoulder than those commonly convert-
ed to .30–06 and .270. This results in a “pinch” between
the rails of some actions at the front end. This occurs when
cartridges attempt to rise and get into line for the bolt to
chamber and close on a round. (Eventually, some width of the
restricted rail sides might have to be removed, but not yet!)
Note: Often the cartridge case bases won’t ease up into the
bolt face under the extractor, which is a must. You must
deal with this problem before doing any further work. If too
much resistance exists for the cartridge case extractor groove
to get the extractor claw to slip into it comfortably, heavy
contact areas on the frontal rails are still off-limits for altering
via grinding.
Actually, resistance often leads to a “lucky” situation. It’s
easy to remove a microscopic amount of metal from the
extractor claw face with a felt-gritted bob in a hand grinding
tool (Figure 29). Work with extreme caution. The extractor
claw contact to case has a slightly rounded contour to match
a tiny flat surface at the bottom of the extractor groove of the
cartridge case.
Basic Metalworking and Machine Tool Operation
However, far too many extractor claws are sharpened care-
lessly to a knife edge. This seems to be characteristic of some
modern Mauser-type actions. Some have sufficient tension on
the cartridge case-to-bolt-face shroud that the tiny required
flat can be created via the gritted felt bob. Believe me, it’s
this critical! A sharp knife-edge extractor claw face is neither
fully functional, nor is it desired for longevity in feeding effi-
ciency. The extractor claw should match the extractor groove.
It will grip better and wear indefinitely.
Another important factor is the slight hump on the lower
edge of the extractor claw. The hump is often too severe in its
tension contact against the cartridge case when it must slide
into the bolt face (under the extractor lip). The across-the-
bolt-face opposing resistance surface is the lower edge of the
bolt face shroud. Usually this has too sharp a corner, which
was left by the original manufacturing milling. Gently hone it
down with an EZE-LAP diamond hone and stone in medium
and then fine surfaces. Be sure not to overdo this. The high
point of the shroud circumference must remain only slightly
rounded and smoothed (Figure 30).
Let’s go back to the extractor. This is where you must work
out and finalize the tiny dimensional and tension factors.
First, note how much tension is on the cartridge case rim
from the extractor when a cartridge head is in the bolt face.
The bolt face and extractor should hold a loaded cartridge
when the bolt is horizontal with the extractor on the bottom
side naturally holding the rim against the bolt face shroud on
40
FIGURE 29—This cone-shaped#240 grit-treated felt bob canmatch the radius of an extrac-tor lip with a knife edge that’stoo sharp. Polish back ONLY,and VERY SLIGHTLY if the claw edge exerts too muchtension for easy cartridge headentrance into the bolt face.
Basic Metalworking and Machine Tool Operation 41
top. There must be enough resistance here to hold the car-
tridge in position if it’s extracted, loaded, from the chamber
to be ejected. Tension must not be so light that the cartridge
drops onto the magazine top or other cartridges in the maga-
zine.
This is indeed a touchy adjustment. If you master it, your
customers will love you (provided they’ve experienced other
maladjusted bolt-action feeding problems). Getting this fairly
heavy “springy” Mauser-type claw extractor into a maximum
functioning-with-ease capability is almost a high-tech preci-
sion job.
If the extractor claw-to-cartridge-rim-recess tension is too
heavy, you’re fortunate. It’s easy to remove metal, but impos-
sible to add it onto these tiny surfaces.
The most efficient method of backing off the usually wrong
knife-edge extractor claw-face edge is to select a gritted felt
bob of approximately the same diameter as that of the
extractor groove. Remove the extractor from the bolt and lock
it up gently between the protective jaws of your workshop
bench vise. With the felt bob (about 240 grit) mounted in a
small electric hand tool, angle your vise so you can reach the
claw while you use the bench for support. A mere touch can
often do the trick.
FIGURE 30—If necessary, youcan grind the groove behindthe extractor claw and itsguide lug a touch deeper toprovide more extractor tension.DON’T let the grinding stonetouch the extractor claw.
The curved gripping face of the extractor claw should never
have a knife-sharp edge to begin with. A flat face to approxi-
mately match the width of the cartridge case recess is also
incorrect, as brass varies according to size and manufacturers.
For example, a .223 Remington rim-bottom extractor-grip-
ping flat is only about 0.025 inch wide, while a Remington 6
mm goes to about 0.036 inch, and the 6 mm Remington B.R.
is at 0.058 inch. Measure them yourself for your own
satisfaction.
The fact is, you don’t need a knife-edge Mauser-type claw
extractor. It’s stronger and more efficient at about 0.025
inch. When you reinstall the extractor claw onto the bolt to
test the cartridge-into-the-bolt-face tension, it may still seem
too heavy—yet dimensions appear close.
In this case, remove the extractor from the bolt again, lay it
on a firm material such as plastic or rubberized vise jaw
inserts, and thump it firmly with a hard rubber hammer.
You may have to use several blows to get a desired slight
relaxation of tension into a husky extractor. It’s a time-
consuming tinkering job, but you’ll be proud of the results.
Whipping Knife-sharp Extractor withoutTension
What do you do if you get a knife-sharp extractor claw with
insufficient tension that drops cartridges and cartridge cases
before reaching the ejector? This is quite common on some
imported new Mauser-type
rifle actions. First, write or call the supplier and complain
long and loud. Then ask for some replacement extractors
from which you can hopefully select one that fits properly or
has sufficient tension to permit modification.
The only other solution is to somehow alter the surfaces
under the extractor where it bears against the bolt body.
Here, you remove a few thousandths of an inch from the
inside of the extractor groove directly to the rear of the claw.
This part of the extractor bears against the bolt shroud head,
with its extractor fore-and-aft positioning lug running in a
groove milled into the front of the bolt just forward of the
lugs (Figure 31).
Basic Metalworking and Machine Tool Operation42
Basic Metalworking and Machine Tool Operation 43
Use a diamond wheel dressing tool to bring an emery cutoff
wheel to the approximate diameter of the bolt body front end
just behind the shroud. Then, trim out an accurate radius to
permit the extractor claw corresponding tension increase
Warning: Don’t trim out anything on the thin part of the
extractor inside that rides over the right locking lug of the
bolt. Here, no dimensional reduction is safe.
Again, all the alterations and adjustments are time-consuming,
tinkering jobs, the accomplishment of which anyone can be
proud. Mauser claw-type extractors weren’t designed to safe-
ly override bolt closures on cartridges just dropped into the
chamber. At times, such a forceful closure will break off the
extractor lip.
Don’t single-load or crowd that extra round into the chamber
over a loaded magazine. You can safely get that last round
loaded using common sense and manipulation. Place it on
top of the loaded magazine and push down. There’s usually
some slack left. With the bolt open, and while holding down
the round, slip the bolt forward easily and pick up the car-
tridge rim under the extractor, move the bolt forward, and
chamber it. Be sure to have the rim under the extractor
when you forward the bolt. There’s “Nuthin-to-it!” except
remembering to do it right!
FIGURE 31—The extractor clawshould exert sufficient tensionagainst the opposing bolt shroudto easily hold the weight of aloaded cartridge, yet permit easyentrance into the bolt face underthe extractor.
Emergency Alteration
If you’ve followed tension and other tolerances carefully,
you’ll know that you should bevel the forward outside edge of
the extractor claw. Without severe extractor claw tension, the
extractor will almost always override the cartridge rim when
the bolt is closed onto a round that has merely been dropped
into the chamber and the bolt closed. However, don’t push
your luck—do it correctly—and then hope you save the
extractor if you do make a mistake and let one slide into the
chamber ahead of the extractor.
Modern, within-bolt-shroud spring-type extractors such as the
Remington M-721, 722, 600, and 700, have spoiled folks on
closing their bolts on chambered rounds. This increases the
possibilities of doing it wrong on the old M-70 Winchesters
and other rifles that have Mauser claw-type extractors. When
you get into the gunsmithing business, keep this in mind
and inform your customers.
Action-rail Tolerances
If you’ve whipped your first extractor-bolt-face alteration, you
can rejoice only for stage one. However, without success in
the first stage, all other efforts are almost in vain. Go slowly,
and think!
Now that nothing prevents the cartridge from properly entering
the bolt face, observe the cartridge as it rises up (or attempts
to) out of the magazine. Getting the cartridge’s semi-rimmed
head to easily (and with proper tension) slide up into the bolt
face was all conducted out of the rifle action. Rifle action
imperfections and variations could wrongly influence your
work.
Next, with only the bolt body and extractor in the action, try
feeding cartridges. Observe whether or not there’s excessive
resistance to the cartridge coming up out of the magazine
front. Often, left and right action rails require a slight trim-
out around their front areas to relieve binding from a new
larger cartridge as it’s pushed forward and up by the bolt
(Figure 32).
Basic Metalworking and Machine Tool Operation44
Basic Metalworking and Machine Tool Operation 45
You can expect such a situation when a military or other
action is barreled to a larger caliber or cartridge. If the car-
tridge body is longer in its full diameter, you must grind out
the section under the top rails’ edges to accommodate it for
any additional length and/or width.
Note: Almost no dimensional criteria for the above task exist.
Trial and error and experience prevail.
It doesn’t matter how careful you are. Here again, you face
the possibility of mistakenly removing too much metal and
having no way to put it back!
The topic of action-rail tolerances came up during a visit with
one of the world’s best known “all-around custom gunsmiths.”
He responded, “After you’ve worked your heart out, are sure
you have everything right, load the magazine, close the bolt,
and watch all the rounds jump out onto the ground when
you open it, you know you’ve gone too far!”
Most problems arise from not doing the aforementioned
extractor altering and careful fitting first, plus carelessly
widening those top rail lips, which initially you shouldn’t
touch. (Only observe the top rail lips for adequate left and
right clearance for the cartridge body to rise up out of the
magazine, as its rim gets under the extractor.)
FIGURE 32—Emery stones, in3/16 inch, 3/8 inch, and 1/2 inchdiameters are a good combina-tion for slight widening ofbetween-the-rails gap andextending the chamber approachhump for longer magnum car-tridges.
Keep in mind that cartridges aren’t supposed to emerge from
the magazine until the bullet, neck, and shoulder are started
into the chamber with the bolt pushing it forward and the
rim getting up under the extractor lip (Figure 33).
It’s difficult to discuss, write, or illustrate all of the details of
successful cartridge feeding alterations. As you study this,
remind yourself: “Don’t grind on those rail edge lips” until
you’re positive it’s required. Then grind only along the front
1 inch of the action’s magazine opening and directly above
the front 1 inch of the magazine box.
Note: Work should progress very slowly at this point. Feed
loaded dummy cartridges out of the magazine after every
slight grinding
or even polishing at front rail edges and observe whether or
not the bullet-neck front end is being pointed at the chamber
opening. Also, check whether or not there’s too much bind or
friction against any portion of the front of the cartridge body.
Excessive rubbing will leave a telltale brass smear on the
inside of the action front rail area.
Caution: Don’t always remove more metal where contact
exists. The narrower front of the cartridge body humps on
left and right rail insides. It must guide the round properly
into the chamber, along with the correct position of the case
base in bolt face and the rail sides in front of it. Strive for a
fitting that allows forward movement of the round into the
Basic Metalworking and Machine Tool Operation46
FIGURE 33—The .338 Magnumcartridge shoulder is 6 mmlonger than 7 and 8 mm for M-98design. For comparison, the.30–06 is also too long. Use anelectric hand grinder with a 7/16inch �� 3/4 inch emery stone toextend between rails, width for-ward. (Don’t touch the top rails’lips now.)
Basic Metalworking and Machine Tool Operation 47
chamber with moderate nonbinding pressure. This takes
time, study, application of all you know, and learning.
Correcting Cartridge Jump-outs
You may be able to save the action, if you haven’t gone too,
too far! Grind out a little more under the rail lips, thus giving
more lip overhang to hold the cartridge body. Don’t touch
the rail lips, as apparently they’ve already been ground off
too much!
I ground too far once with a .35 Improved Whelen wildcat
cartridge on a 1903 Springfield army action. This much fatter
(most of the body taper removed) case caused serious feeding
difficulties. Eventually diving onto it with a vengeance, I went
too far and got jump-outs! Gradually widening the area
under the rail lips saved the action. The widening allowed
the “fat” rounds to be fed so perfectly we could even load the
magazine with fired empties and feed them into the chamber
without hang-ups! Much was learned from this bad, then
lucky, experience. (Use fine-grit felt bobs to polish surfaces.)
Influential Magazine FollowerDimensions
You can experiment with cartridge follower dimensions via
adding small layers of soft solder and at times epoxy, then
testing. This enables you to decide on changes without
experimental welding to scar up or wreck a perfectly good
follower. You remove solder or epoxy and add welded steel if
you determine that it’s warranted.
Even a slight pinch-together of the top of the magazine box
changes cartridge feeding, as does a bit of spreading the top.
There’s a lot of work, study, and experimenting to do before
you become a master of cartridge feeding alterations. But it
will save you many headaches and extend your reputation
into far corners, besides earning you some money.
Wrong Feeding Diagnosis on MilitaryKrag Rifle
I had a .30–40 bolt-action Krag rifle with the magazine car-
tridge feeding cutoff removed. This left a partial cylindrical
opening in the bottom of the bolt-way. The bottom edge of
every cartridge rim would catch down into this and hang up
as the bolt was pushing it forward. The front bullet end of
the round would be tipped down firmly against the bottom of
action chamber approach area.
Someone had done useless, unnecessary grinding at the
chamber approach bolt-way bottom, damaging the action
because of a 100% wrong diagnosis. The proper repair con-
sisted of merely lathe-turning a small steel rod the exact
diameter of the Krag rifle’s cartridge cutoff shank. I then
ground it to conform to its original “on” position shape, and
staked it into position with a few center punch dimples on its
blind side. Think, and go carefully. Accurate troubleshooting
is one of the gunsmith’s greatest attributes.
Basic Metalworking and Machine Tool Operation48
Basic Metalworking and Machine Tool Operation 49
Self-Check 4
Fill in the blanks in the following statements.
1. _______ in inch, inch, and inch diameters are a good combination for slight wideningof the between-the-rails gap and extending chamber approach hump for longer magnumcartridges.
2. It’s easy to remove a microscopic amount of metal from the extractor claw face with a_______ in a hand-grinding tool.
3. Some modern Mauser actions suffer from _______ that have been sharpened carelesslyto a knife edge.
4. Some new, imported Mauser-type rifle actions have a knife-sharp extractor claw, with_______ , that drops cartridges and cartridge cases before reaching the ejector.
5. An extractor claw should exert sufficient tension against the opposite bolt shroud to easily hold the weight of a _______ , yet permit easy entrance into the bolt face, underthe extractor.
Check your answers with those on page 107.
THE LATHE: KING OF GUNSMITHING TOOLS
• Uses for the lathe are endless:
• Making the tiniest screw
• Facing of sears and working parts accurately with a tool
post grinder
• Rebuilding surfaces
• Opening bolt faces for larger cartridges
• Making firing pins
• Cutting dovetail slots with your milling attachment
• Threading, chambering, and fitting new barrels (Figure 34)
Basic Metalworking and Machine Tool Operation50
FIGURE 34—Shown is thelathe, the shop’s foremosttool. Steady rest is a necessityfor threading between centersand chambering.
Basic Metalworking and Machine Tool Operation 51
A Barrel Vise
A heavily built, solidly mounted barrel vise is a must for
removal and proper installation of new barrels, or others
removed when improving chambers. Don’t make the mistake
of anchoring a barrel vise to wooden benches or walls. Pour
a concrete pillar or heavy rectangular base through your
building floor into the ground. Set your mounting bolts into
the new wet concrete through an approximately 1/2 inch �
7 inches � 10 inches steel plate, in position to mount the
vise over the protruding bolts after the cement cures. This
arrangement will last forever and never tear out walls, tip
over, or break benches. Mine is on a concrete block 17 inches
� 20 inches � 32 inches thick. No barrel removal has ever
defied it (Figure 35).
While my vise is a Vickerman, it resembles the Brownell’s
THREE-V in both vise and wrench. Hardwood and lead barrel
sleeves have often failed me. Steel seldom gives a perfect to-
the-barrel fit and scars the barrels. I use a mixture of bullet
lead and bearing babbit, which is harder. By fitting a pair of
wooden slats to the flat sides of the bottom half of the vise,
the barrel is inletted to rest slightly above center, so the
sleeve halves will have cinch-up space.
FIGURE 35—You’ll get trouble-free barrel removal and instal-lation with the heavy barrelvise anchored in concrete.Precast fitted barrel sleevesgive positive grip. The 8 poundlead hammer is shop-cast.
Basic Metalworking and Machine Tool Operation
After you plug the vise cinch-up screw holes in the bottom
half, pour the molten metal into the lower vise half around
the barrel. You might have to do several practice pours
before the sleeve half cast will shape up properly. Be sure
to position everything identically for your second-half sleeve
pour. This assures a perfect fit. Initially, you should position
the barrel as near to the receiver as possible. This provides
more grip area and more rigidity.
The best sleeves are made from a metal mixture that gives a
slight ring when gently tapped with a steel tool. Use your
metal stamps to mark the sleeve set. (Examples: #3 Shilen,
Douglas #4, Springfield, Enfield). This saves much time later.
File the sleeves neatly near the barrel vise. A space, 11/2 �
21/2 inches, provides ample room for drilling to accept an
empty G.I. .30–06 case as a station peg. Each 17 inches of
this rack holds 10 sleeve sets with their rubber band keep-
ers. The racks are strapped to the chimney with stovepipe
wire to provide an easily removable no-drilling arrangement.
This system provides you with perfectly fitting, readily avail-
able barrel vise sleeves. Never make a nonfitting sleeve set
to remove a different barrel. Take time to cast a perfect set.
Add it to your tools, to be there next time you need it.
Note: Eventually, you’ll need a Kleinendorst Remington M-700
action adapter tool for removing the round Remington actions
with that separate recoil lug, which can’t otherwise be kept
aligned. Frequently, it’s necessary to improve the gripping
onto the action by using rosin or sheets of emery cloth.
Gunsmith-built Action Wrench Hammer
The 8 pound lead hammer in Figure 35 has a 22 inch handle
of scrap 7/16 inch pipe. Initially, I drilled several cross-holes
through the head end and then positioned it inside an empty
food can, which served as a casting form. It’s easy to recast a
new hammer head when one gives out. Some gunsmiths use
long-handle extensions for their barrel wrench, and you
might even proceed to precision torque wrench cinch-ups for
fine accuracy work. Remember, gunsmithing-inclined folks
are among the world’s most inventive people. You can make,
fashion, and improve many of the gadgets and tools you’ll
need and use.
52
Basic Metalworking and Machine Tool Operation 53
The Complete Shop
As financial considerations allow, you’ll need more than a
good lathe, barrel vise, and action wrench hammer. A “com-
plete” shop requires a drill press, bench grinders, electric
hand grinders, acetylene and electric welding outfits, several
buffing machines, and a vast assortment of hand tools. An
air compressor, blasting gun, and a long-gun size blasting
cabinet for glass bead treatment of firearms prior to bluing
are modern frontline essentials. You’ll be adding more tools,
respirators, eye goggles, and gadgets the rest of your life!
Details of a Barrel Fitting
Instead of chitchat generalizations that can confuse and
dampen your lust to start real gun work, let’s follow a barrel
installation. Prior to attempting this task using a lathe,
you should complete a basic course in lathe operation and
metalworking. Gun barrel fitting has intricacies of its own.
We’re working with thousandths of an inch. Errors can be
dangerous.
To perform accurate work on a lathe, you must mount the
lathe firmly on a heavy metal or hardwood timber bench and
bolt it to a concrete floor or into the ground support pillars.
You must level the bench top and lathe with a machinist’s
level and recheck it frequently. My machine is a Sheldon
XL 56 with a 13/8 inch hole in the spindle, approximately
36 inches between centers. It can handle 54 different threads
(feeds), but none metric, which modern gunsmiths may need
and should consider purchasing.
Numerous quality chrome-moly and stainless steel barrel
blanks are available from reputable barrel makers. They
range from lightweight through heavy-target contours offer-
ing various rifling twists. While we can’t settle the proper
twist controversy, it’s almost entirely related to the weight
and length bullet used. Ed Shilen, of bench-rest-shooting-
barrel manufacturing fame, said of the 6 mm, “If you plan to
use 68- and 70-grain target bullets, get a 1-in-14 inch twist.
A 1-in-12 inch twist stabilizes 75 to 85-grain projectiles . . .
and if you want a 100-grain bullet hunting rifle, it requires a
1 in 10 inch twist.”
Data for proper twist selection of your barrel blanks is avail-
able from many sources and is a must for every gunsmith’s
bookshelf. It’s usually impractical for the average gunsmith
to stock heavy blanks and turn them down, as manufacturers
have superior equipment to handle this and provide a contour
selection that’s more than adequate.
Removing 11/2 Inches from the Muzzle
Due to slight internal muzzle damage possibilities during
manufacturers’ turning of barrel blanks, I cut about inches
from the muzzle. Then I face off the heavy breech end to at
least the outside thread shank diameter of the barrel I’m fit-
ting. A chamber cut on this end of the barrel removes any
imperfections that might exist near the blank end.
My system of threading and chambering between accurate
lathe centers requires the use of piloted center drills to recut
new working centers. You grip the breech end of the barrel in
an accurate three-jaw chuck and use a floating toolholder or
tail stock center metal pad to allow the piloted drill to follow
its center. After you cut the breech new center, switch ends
of the barrel in the chuck using a slightly compressible cir-
cumference shim on the small end of the tapered muzzle to
better grip and center it. Use the lathe in back gear (slow
speed) and proceed
as you did with the
first center cutting
(Figure 36).
Basic Metalworking and Machine Tool Operation54
FIGURE 36—The three-jawchuck holds the barrel forcutting a new center with a piloted center drill in afloating toolholder.
Basic Metalworking and Machine Tool Operation 55
Setting Up the Barrel between Centers
Replace the head stock chuck with a head stock center and
faceplate. Then, affix the lathe dog to the muzzle end of the
barrel. Next, position the live tail stock center in place of the
floating toolholder or tail stock thrust pad. Place the barrel
blank between lathe centers and position your steady rest
slightly forward of the barrel’s first large-diameter taper, lub-
ing barrel and center rest bar surfaces with high-viscosity
grease.
Prior to steady rest positioning, you must move your tool
post unit between the steady rest and tail stock. At this
point, I advise you to take a slight truing cut on the large
breech section of the barrel. All barrel blanks aren’t perfect
here where the steady rest must be moved for perfect cham-
bering after threading.
After the large breech end of the barrel blank is turned true,
the barrel shank, can be turned down to length and proper
diameter for the action you’re fitting it to. If the original bar-
rel shank thread was slightly loose in the action, the new
shank can be about 0.003 inch larger in diameter.
Set up your threading bit in the tool post (sharpened and
checked for shape and center). Set the compound at 29
degrees. Follow normal threading procedures, advancing
your cuts on the compound, from 0.001 to 0.003 inch per
pass. Then, return the crossfeed to your starting pass to
zero each time before dropping the half-nut lever for another
pass cut.
Caution: Don’t practice threading on a first barrel fitting.
You need some manual dexterity to accurately time the lifting
of the half-nut lever and swing-back of the crossfeed at the
instant the threading bit nears the barrel shank shoulder.
Watch your compound advance figure as you cut several
thousandths each pass. For instance, the double depth of
the 16 threads per inch (TPI) thread of a Remington M-700
is 0.081 inch.
As the thread approaches a “V” and the depth advance figure
gets close, stop the lathe, back off the tail stock, and try
turning the action onto the barrel. With the action started
onto the barrel shank, advance the cut only 0.001 inch at a
time, trying the action after each cut. After the action will
turn about halfway up the shank, mark with chalk the lathe
dog leg position on the faceplate so you can return it for
more threading, if necessary.
Remove the barrel from the lathe, lock it up in the barrel
vise, affix the action wrench to the action, and carefully
work the action onto the high-viscosity-greased barrel shank.
Usually you can hand work the action onto the new thread,
providing a snug fit and better accuracy. If you can work the
action onto the barrel shank, remove it from the barrel vise
and return it to the lathe. Then, take another slight cut or
two (provided you’ve marked the lathe dog leg position on
the faceplate, and have been careful not to move the dog
during your barrel vise work).
Reaming Chamber
After assuring yourself that you can turn the action onto the
barrel shank, return the barrel to the lathe between centers
and dismantle the threading setup. Then, move the steady
rest rearward onto the trued heavy chamber end of the bar-
rel, just forward of the thread shank. Replace the tail stock
center with floating toolholders or a pad for chambering
reamer feeding. With the lathe still in back-gear, start with
a roughing reamer, using cutting oil and feeding slowly.
Alternate use of the finishing reamer frequently to keep
the reamer pilot in a guiding position in the bore. Clean
chips from reamers at every 1/8 inch advance.
There’s a convenient system for following chamber depth
to correct headspace as you ream. Insert the correct caliber
headspace “GO” gauge into the original barrel and measure
its protrusion with a depth gauge (Figures 37 and 38).
As the GO gauge protrusion nears that of the original barrel,
back the tailstock off and turn the action with the stripped
bolt onto the new barrel shank.
Note: Carefully wipe out the chamber and section of the bore
in front of it prior to each check with the gauge.
Basic Metalworking and Machine Tool Operation56
Basic Metalworking and Machine Tool Operation 57
With the gauge in the chamber and the action turned up
snug, any gap remaining between the barrel shank shoulder
and the front face of the action is the depth you must yet
ream to reach correct headspace. If you still have a little
gap left here, ream in almost microscopic stages, advancing
the tailstock feed so slightly as to barely get feel-in-chamber
FIGURE 37—You can compareshank length plus GO head-space gauge measurementwith the original barrel, aschamber reaming nears com-pletion. Keep this measure-ment, and keep checking thenew chamber you’re cutting.
FIGURE 38—Use a depthmicrometer to check shanklength of a new barrel for M-700 Remington. Keep the toolpost and bit in position untilreaching the final dimension.
Basic Metalworking and Machine Tool Operation
contact. Allow the lathe to turn about 5 seconds to be sure
all cutting is cleared at that advance. Now, clean the cham-
ber and try turning the action all the way onto the shank
shoulder.
If it goes, try the “NO GO” gauge. If the action goes all the way
with the bolt closed and the NO GO in the chamber, you
have correct headspace only theoretically. This is because
when you transfer to the pressure of the barrel vise cinch-up,
head length will reduce by at least an average of 0.002 inch.
So, before you take your almost-barreled action to the barrel
vise, you’ll likely need another scrape-cut in the chamber.
Barrel Vise Cinch-up
If the bolt closes on the GO gauge and won’t close on the
NO GO after a solid cinch-up in the barrel vise, you’ve just
completed your first touch rebarreling job. Sometimes the
cinch-up gains enough so the bolt won’t close on the GO
gauge. In this event, take the barrel back to the lathe for
another dainty chamber scrape-cut. Don’t attempt to hand-
ream when the barrel and action are locked up in vise sleeves,
as the power of these screws is mighty. The chamber is actu-
ally slightly compressed, and reaming will take excessive
cuts, with the possibility of leaving the chamber out-of-round
once the tension releases. Naturally, you remove the action
before going back to the lathe.
Over-reaming
Getting a chamber too deep, permitting bolt closure on the
NO GO gauge, does happen now and then in spite of all
caution. This requires further lathe work, facing off the
overdepth amount of the chamber from the barrel shank
shoulder and also the rear face of the barrel. Then, you
must rechamber the rear chamber edge.
Shop Methods Differ
Some gunsmiths might question whether tight-thread and
precise barrel fitting are necessary for ordinary sporting pur-
poses. It can certainly do no harm, and precision-wild bench
rest gunsmiths and shooters have proven to the world that
58
Basic Metalworking and Machine Tool Operation 59
every minute detail makes a difference.
Another method of handling a barrel blank for threading
and chambering is through the head stock spindle hole and
chuck with a centering device on the left end of the spindle
hole. Use a dial indicator to adjust the barrel to dead center.
Barrel Shank Specifications
The February, 1962, issue of the American Rifleman magazine
(pages 28 through 30) has a “barrel threads” specification
display that gives standard dimensions and thread data for
50 different guns. This valuable addition to any gunsmith’s
library provides much-needed information when you don’t
have an action or barrel to copy. I’m told the list has been
updated since 1962 to contain even more thread specifica-
tions. The 1962 edition serves me just fine. You could find
out more about later updates by contacting the magazine.
Stainless Steel vs Chrome-moly Barrels
Chrome-moly vs stainless steel barrels sends me seeking
information from the barrel makers and the competitive target
and bench rest shooters. These men and women wear out
more barrels than most sportsmen users own. From the
accuracy standpoint, Ed Shilen, a long-time barrel maker and
bench rest competitor, told me there’s little accuracy difference
between stainless and chrome-moly. The problem is that
many different alloys are being used, and even more were
tried in the past. Ed says his experiences with the best
grades of stainless #416 and a special chrome-moly 4140
show a gilt-edge accuracy loss at 600 to 800 rounds for
the chrome-moly. Stainless can go to 2,000 to 3,000 rounds
in the smaller bench rest calibers. In larger calibers, the
stainless lead decreases to about 25 percent, with suitable
hunting accuracy going far beyond this for both steel types.
For average gun owners, the chrome-moly price isn’t nearly
as high as the stainless and is therefore often preferable.
However, stainless is easier to clean, won’t pit or rust, and
machines more easily at the gunsmith level.
Shop Tips
Don’t hurry. Plan your work in detail. An instructor once
told me, “If you have 10 minutes to do a problem, take seven
to figure out how to do it, and take three to do it.”
Provide yourself with good tools. Consider spiral-fluted,
removable pilot reamers for as much of your chambering
as possible (Figure 39). The removable pilot feature permits
you to exchange pilots for doing fine work.
Caution: A slightly loose pilot won’t guide the reamer perfectly,
and one that’s too tight may scar the surface of the lands.
Barrel maker Shilen says his 6 mm barrel bores are running
0.236 to 0.237 inch. Bench rest folks usually prefer the tight
bores. Your regular 0.237 pilot won’t do this job. A pilot
selection enables you to get at it immediately.
Keep all your equipment in excellent condition, lubricated,
sharpened, etc. When chambering, don’t forget to remove
reamers from the chamber and clean chips from the reamer
and chamber at every 1/8 inch advance and then after each
touch on the final approach to correct headspace.
Basic Metalworking and Machine Tool Operation60
FIGURE 39—Spiral-flutedpiloted chambering reamers(center) provide outstand-ing performance. Pilots prevent possible scarring of bores.
Basic Metalworking and Machine Tool Operation 61
Self-Check 5
Indicate whether the following statements are True or False.
_____ 1. To do accurate work, you must level the bench top and lathe with a machinist’slevel.
_____ 2. When replacing barrels, if the original barrel shank thread was slightly loose in theaction, the new shank can be about 0.020 inch larger in diameter.
_____ 3. Spiral-fluted, removable pilot reamers are helpful for chambering barrels.
_____ 4. Generally, stainless-steel barrels demonstrate a gilt-edge accuracy loss much morequickly than chrome-moly barrels.
_____ 5. You need a heavily built, solidly mounted barrel vise to remove and properly installnew barrels, or other barrels removed for chambering.
Check your answers with those on page 108.
BOLT FACE OPENING (MANGUMIZING) IN THE LATHE
Shortly after World War II, surplus military bolt-action rifles
flooded the market to end a five-year shortage of hunting
and sporting arms. It was also a time when the Weatherby
belted magnum craze hit the nation. Few gunsmiths had the
tools, equipment, and know-how to do bolt face magnumizing
properly.
To magnumize properly, you of course need a larger cham-
ber. You enlarge the diameter of the bolt face 0.063 inch to
0.065 inch and grind off the extractor lip accordingly while
holding the proper shape and tolerances. Most of the larger-
belted cartridges require magazine lengthening and grinding
away some of the lower locking lug’s backup metal. You need
to grind out and shape the feed rails of the action to accom-
modate the fatter cartridges. A lot of careful metalwork is
involved, and it’s often said that anyone capable of doing a
good job on one of these conversions could do anything.
World-known gunsmiths Al and Roger Biesen, Spokane,
grinned wryly when stating the following. “When you think
you’ve finished your job, gently load three or four rounds into
the magazine to test the feeding. Close the bolt . . . and when
you open it sharply all rounds jump out of the magazine,
alas-plus, you’ve gone too far!”
Sometimes you can avoid ruining an action by undercutting
or grinding a little more off the heavy part of the rails above
the magazine box, but being careful not to widen the top thin
edges. This part of the conversion requires a lot of time and
advance study of factory-built actions that do feed.
Selecting military actions for magnum conversions isn’t easy.
The safety factor must have first consideration, and depend-
able information on the foreign actions (many built with slave
labor) is almost nonexistent.
Fortunately, most gunsmiths are aware of those below
800,000 numbered case-hardened, low-carbon steel U.S.
Springfield M-1903 actions. All but a few of the couple hun-
dred finals utilized single heat treatment, where most of the
Basic Metalworking and Machine Tool Operation62
Basic Metalworking and Machine Tool Operation 63
problems resulted from irregularities. The irregularities caused
the case hardening to go all the way through, making them
brittle and sometimes highly dangerous even with normal
.30-06 loadings.
Such actions were followed by double heat-treated actions,
which gave additional strength and were considered adequate
for ordinary use (but not for modern magnumizing). The con-
version of number 1,275,767 Springfield Arsenal to nickel
steel WD2340 provided a healthy safety factor. Rock Island
changed to double heat treating in 1927 with number
285,507. After 319,921, they used both the original class C
steel, double heat-treated, and nickel steel. When the barrel
is removed from the receiver, you can see the letters NS
stamped on front of the receiver.
While the better Springfields make up into fine sporting
rifles, and many have been magnumized, the danger is readi-
ly apparent. Most of us don’t recommend higher-pressure
cartridges in them. The 1917 Enfields of Remington and
Winchester manufacture have been used for all types of
magnumizing, but the Eddystone, made in the USA to British
specifications, is extremely hard and difficult to drill and tap.
It’s a “no-no” for magnums.
German and other manufactured Mauser M-98s range from
soft as a .22 L.R., to good and tough. Accurate information
relative to metals, treatment, and safety is difficult to obtain.
Many Mauser M-98 actions have been heat-treated again
and made into fine sporting rifles. Even a Rockwell hardness
test isn’t a strength guarantee, as no one is certain of the
metallurgy.
Through the years I’ve drilled, tapped, and rebarreled hun-
dreds of Mauser M-98s to standard calibers. I selected actions
for quality in a nontechnical, not-recommended manner
(though I’m certain it has some merit). I always drilled and
tapped the actions first. If they drilled and tapped easy-soft,
I rejected them. If they drilled with some evident toughness
and the taps had to be ultrasharp and be used carefully,
I okayed them. There were no headspace setbacks on the
ones I thus converted. I also didn’t overload! Basically, you’re
on your own with military actions. No one can be sure.
Basic Metalworking and Machine Tool Operation64
You need a tool post grinder, larger and more rigid than the
Dremel Moto tool types, to open bolt faces (Figure 40). Mine
is a Dumore and other makes of the same size are available.
A grinding stone no larger than 7/16 inch diameter by about3/4 inch new length is more rigid than shorter ones. It can
be chucked close, supporting nearly all of the mandrel. A
grinder with little to zero end-play is necessary for accurate
work. Dress the stone to give a sharp front corner edge and
have straight sides with a dressing brick or diamond dresser.
Setting up the bolt in the lathe calls for an inside-the-bolt
threaded center plug to replace the bolt sleeve as snugly as
possible. I originally made mine with a lathe for Mausers,
Springfields, and Enfields. Now you can use Brownell’s heat
sink plugs by merely cutting a center in the outside end if
you’re going to use a lathe dog. Otherwise, grip the bolt rear
end with your three-jaw chuck, somewhat gently to begin with,
while positioning the tailstock center into the bolt face firing
pinhole. Then, tighten the head stock chuck. Position the
steady rest directly behind the bolt lugs. Thus gripped with
front end centered in a steady rest, back off the tailstock
center and move the tool post grinder into position. Carefully
center the grinding stone in the bolt face with only touch
contact, as you don’t want to deepen the bolt face (Figure 41).
FIGURE 40—Keep a toolpost grinder’s emery stonedressed frequently and itscorner sharp.
Basic Metalworking and Machine Tool Operation 65
The lathe should be in back-gear (slow). You should mount
the tool post grinder bracket at 90 degrees so you can use
the compound to keep a wearing grinding stone onto the bot-
tom of the bolt face. After turning on the lathe, move the
cross feed so the grinding stone (with grinder running) barely
touches inside the bolt shroud. Allow the grinding stone to
grind clear before making easy additional feed advances. It’s
touchy, so be careful!
Note: Keep close measure on your progress and back out
the grinder frequently to redress the side of the stone. This
keeps its corner sharp enough to grind a clean right angle
at the junction of the bolt face and shroud bottom. Grind
just enough to give the magnum belted case rim a few thou-
sandths of an inch clearance. Use a factory-belted magnum
bolt for comparison and establishing correct dimensions.
If you have a bolt shroud that you cut with a carbide bolt
opening bit, this works fine. There’s a rotary burr (carbide)
available for in-tool post grinders’ use. Remember, super-
hard cutters can shatter easily. While the grinding stone
might take more time and touchy application, it has worked
best in my shop. After doing a few of these jobs, you’ll per-
haps join our crowd of “new magnum actions” lovers.
FIGURE 41—The three-jawchuck grips the rear of thebolt body. The firing pinhole was used to line withthe tailstock center. Thesteady rest was positionedand the toolpost grinderwas aligned to enlarge thebolt face.
Precision Sear Facing with Mini-toolPost Grinders
When you can afford it, purchase three to six small electric
hand grinders such as the Dremel Moto tools (Figure 42).
Having your most frequently used stones, cutters, or acces-
sories chucked and ready to use saves time (Figure 43). In a
busy shop, the need for them is endless. You can’t accurately
shape, cut angles, and grinder-turn hardened pins or parts
by hand.
Basic Metalworking and Machine Tool Operation66
FIGURE 42—Shown is aDremel Moto tool in the lathetool post grinder bracket,readying for sear surfacing.
Basic Metalworking and Machine Tool Operation 67
Figure 44 shows an M-94 Winchester hammer being held in
a four-jaw chuck, with the Dremel tool post grinder almost
in place to commence a straight, microscopically undercut
grinding pass. The sear is worn slightly rounded, providing
too light a trigger pull that can be dangerous. The hammer
can be tilted upward in the chuck-hold to get sufficient
undercut (Figure 44).
FIGURE 43—Having extraDremel or other electricgrinders with the most-usedstones and cutters in placesaves much time.
FIGURE 44—A 0.023 inch ��15/16 inch emery cutoff wheelin a Dremel tool post grindercan make a perfect searrecut. The four-jaw chuck per-mits alignment adjustment.
The cutting stone is an emery cutoff wheel, 0.023 inch in
thickness and 15/16 inch new diameter. They’re brittle, easily
broken, and you must handle and feed them carefully, never
leaving them chucked up in your grinder. To remove the cut-
ting stone from the chuck without breaking it, loosen the
chuck easily, grip the mandrel with a small vise grip, narrow-
jawed pliers, or side-cutter, and pull from the chuck. Store
the mandrel with mounted cutoff wheel in a hole-base away
from contacts with other accessories or tools. There’s a lot of
life in just one of these discs if you care for it properly.
You can do a professional job of grinding screwdriver slots in
newly made screws with this setup. You can grind retaining
pin notches easily into newly made firing pins by using a
larger-width grinding stone. After familiarizing yourself with
some basic uses for the small tool post grinders, your inven-
tive mind will come up with dozens more. Handheld uses
for these grinders of metal, wood, and glass are endless.
Furthermore, having several grinders keeps you going in
case one breaks down.
Drill Rod for Making Parts
A tool steel drill rod for small parts making is available in
various lengths of round, square, and flats from Brownells.
Tempering instructions come with the rod. Lasalle “fatigue
proof” steel rods are also available in sizes inch, 1/4 inch,5/16 and 3/8 inch. The Lasalle rod has a higher ratio of man-
ganese to carbon, is very machinable, and tough without
being brittle. Also, it doesn’t require heat treating like low-
density mild steel. It’s ideal for firing pins, screws, spring
guides, and other parts subject to stress and repeated shock.
You can use parts made from Lasalle steel right away, thus
saving time (Figure 45).
Basic Metalworking and Machine Tool Operation68
Basic Metalworking and Machine Tool Operation 69
W-1 Water-hardening Drill Rod
The W-1 drill rod is a fine-grained commercial-quality steel
containing 1 percent carbon, 0.4 percent manganese, and 0.2
percent silicone. You can use it for making dies, punches, and
other tools or parts that require a lot of hardness and a tough
inner core for top strength. It works well for pins for guns.
If an unusual depth of hardness is needed, you’ll need to
heat the parts from 1450 to 1600 degrees F. If a furnace isn’t
available, use 1450 Tempilaq. Keep at this temperature for
a few seconds, then quench in an 8 percent brine solution,
made from 3/4 pound rock salt in one gallon of water.
Tempilaq is available from Brownells in various temperature
degree ratings. Simply brush it onto the metal, and when it
reaches specified temperature, it melts. That’s the time to
quench.
To temper, give the part a one hour draw at the following
temperatures to result in the Rockwell hardness shown:
FIGURE 45—Shown are M-94Win. firing pins on the left andM-336 Marlin on the right, allbroken uniformly. Dry firingand excessive hardness isresponsible for such breakage.Having a drill rod supplyenables gunsmiths to makemany parts.
A round, 0–1 oil-hardening drill rod contains 0.95% carbon,
1.2 percent manganese, and 0.25 percent silicon. It’s available
in 1/4 inch round and larger. It’s characterized by superior
dimensional stability, machinability, and smooth finish. It
has a top rating for general shop use in dies, parts, tools, and
punches. Tempering and hardening are very similar. Heat to
1475 to 1525 degrees F. In lieu of a controlled furnace, again,
you may use Tempilaq. Hold at the 1500 Tempilaq tempera-
ture for a few seconds and then quench in light quenching
oil. Following this with a one hour draw gives the following
Rockwell hardness.
An unusual feature of these steels is that they have a low
draw temperature to achieve maximum torsion impact
strength. Drawing can be done in a kitchen oven, or you
can make a small furnace with furnace brick and a simple
controlled heat element.
Basic Metalworking and Machine Tool Operation70
FseergederutarepmeT ssendraHCllewkcoR
denedraHsA 76–66
002 76–66
003 56–46
004 26–16
005 95–85
006 55–45
007 15–05
008 74–64
FseergederutarepmeT ssendraHCllewkcoR
denedraHsA 56–36
003 46–36
004 26–16
005 06–85
006 65–45
007 35–15
008 84–64
009 54–34
Basic Metalworking and Machine Tool Operation 71
Self-Check 6
Fill in the blanks in the following statements.
1. You would need a _______ larger and more rigid than the Dremel Moto tool types foropening bolt faces.
2. To accommodate belted magnum cases, World War II military bolt-action rifle bolt faces required enlargement from _______ to _______ and grinding off the extractor lipaccordingly, while holding proper shape and tolerances.
3. _______ , available from Brownells in various temperature degree ratings, is a solutionwhen heat treating without an electric furnace.
4. The “NS” stamped on the front of Rock Island Arsenal receivers stands for _______.
5. Lasalle _______ steel rods are ideal for making firing pins, screws, spring guides, andother parts that are subject to stress and repeated shock.
Check your answers with those on page 108.
SHAPING MUZZLES
Growing Barrel Muzzles(Sporters/Target)
There’s been a lot of propaganda on the value of various
shapes of muzzle crowns. Theoretically, some have said that
shapes tame or control the violence of muzzle blast gases
that might start bullets on a shaky route. As a lifetime com-
petitive shooter, World War II firearms’ instructions veteran,
and gunsmith since World War II, I’ve never been able to
prove such a theory.
From the accuracy standpoint, there seems to be no magic in
any form of muzzle finishing other than a cleanly trimmed
bore edge, with no burrs or metal rollover whatsoever. A
clean bore edge takes a supersharp piloted center drill or a
nonthroated reamer. Pushing and pulling a soft cotton patch
through that muzzle will indicate whether or not there’s any
microscopic bore-edge burring that picks up the tiniest fuzz
off the patch.
Only a 100 percent perfect, unobstructed bullet getaway at
that muzzle edge provides accuracy. Forceful polishing, grit-
loaded balls, or bevels almost always give a slight muzzle-bore
edge rollover that can be accuracy suicide. The old M-52
Winchester .22 L.R. target rifles had a flat muzzle finish
(carefully deburred). Its follow-up competitor, the Remington
M-37, had what I call a target-recessed crown. The crown is
a simple facing slight step-down cut from the bore partway
across the muzzle face to protect its edge from bump dam-
age. The barrel on the right in Figure 46 is a similar step-
down target crown.
The center muzzle in Figure 46 is the crescent-moon, rounded
sporter type, used on most factory and hunting weight arms.
The muzzle on the left shows a simple 60 degree piloted center
drill cut with a flat surface beyond and out to muzzle diame-
ter. This might not be as fancy, but it protects the bore edge.
This is your muzzle-finish priority.
Basic Metalworking and Machine Tool Operation72
Basic Metalworking and Machine Tool Operation 73
You can always play with odd angles and shapes in your spare
time, which busy gunsmiths seldom have. While learning,
then working with gunsmithing, you’ll experience surprising
and amusing situations like the following.
One of our competitive, outstanding, four-position target
shooters (but somewhat rough in nature) displayed his newly
hack-sawed-off barrel shortening. The saw-off was jagged by
gunsmithing standards. “My gawd,” I snorted, “let me put
this in the lathe, face it off right and perfect the bore edge.”
“Shoots ta beat hell,” he assured me. “More likely shoots all
over hell,” I answered. He wouldn’t let me touch it! So smile
on your way back, with the checks from the other guys. And
never quit learning!
How to Crown (Face-off) ShotgunMuzzles
Shotgun barrel facing or crowning is as important as getting
perfect metalwork at the exit muzzle edge of rifle barrels.
Anything that interferes with uniform muzzle shot charge
escape is probably detrimental. Fortunately, it’s initially easy
to prevent. It’s a matter of follow-up when you correct the
nicks on a damaged muzzle caused by careless gun-handling.
What can also happen is muzzle cutback, made necessary by
muzzle mud or snow obstruction blowup.
FIGURE 46—On the right isthe typical target barrel step-down crown with bore- edgerelief. In the center is cres-cent-moon sporting crown withbore-edge relief. On the left isa deeper 60 percent centerrelief giving same protection.Take your pick!
Muzzle cutback usually calls for removal of 21/2 inches or at
least a portion of it (that comprises your shotgun barrel’s
choke). There are two solutions. First, you can install any of
the various choke, screw-in or screw-on adapter tubes, as
well as the adjustable collet types. Next, you can work a
choke back into it with the help of a B-Square swaging tool,
which includes complete instructions. It consists basically
of the gradual tightening of a heavy steel roller system, as
you rotate the unit from about 21/2 inches back toward the
muzzle.
The only accurate progress analysis is to unhook your tooling
system after each pass and take the gun out and shoot it
for patterning. Such a process is slow; so it’s possibly a
slack-time or wintertime project. Nonetheless, it can produce
surprising results.
For example, a single-shot, 16 gauge “junker” with a blown
muzzle rested in a dusty corner of my shop for years. One
snowy subzero day, I built a new firing pin, devised a hammer
spring, and tested the B-Square Choking tool. It worked.
After a few passes with those high-pressure steel rollers,
shooting tests proved I had a tight, full-choke pattern.
Next, I faced off the muzzle, clean and true. I could have
done it in the lathe with a lot of careful setup work. At that
time, Jack McIntyre of Troy, NC, provided me with a sample
of his shotgun barrel facing tool. It consisted of nylon pilots,
five inches long, in front of a disk-shaped file and brace-and-
bit type handle (Figure 47).
The long pilot brought the cylindrical file into perfect align-
ment with the bore. With the barrel locked in a padded vise,
the brace-and-bit handle enabled me to true up the muzzle
face in minutes, accurately and in less time than a lathe
setup would have taken. New gunsmiths should consider
this. All in this world isn’t yet totally mechanized, especially
gunsmithing. That handwork at the bench is still often what
separates the amateurs from the professionals.
Basic Metalworking and Machine Tool Operation74
Basic Metalworking and Machine Tool Operation 75
The McIntyre tool comes with one nylon sleeve (pilot) of your
choice of gauges: 12, 16, and 20. It’s available in two sizes,
small for finishing single barrels, and large for single and
double barrels. This tool shortened facing jobs to 3 to 5 min-
utes. Time wise, I couldn’t even compare it to doing a lathe
setup.
However, there are possibilities of making a version of the
McIntyre tool to fit into lathe tail stocks. You budding young
gunsmiths have the world before you, as Jack McIntyre has
turned his inventiveness and skills elsewhere.
Remember that a mechanical flat facing tool still leaves a
sharp muzzle edge at the bore front. Rotating a beveled
Cratex rubber-grit impregnated or grit-treated felt polishing
bob inside the muzzle edge neutralizes this knife-sharp edge
in seconds. You can rotate the outside edge gently on a firm-
faced gritted sailcloth buffing wheel.
If the project involves a choke installation, the outside edge
will be against a choke adapter sleeve, out of sight, out of
reach. This makes deburring of no significance, and in fact it
could even contribute to a tighter seal.
FIGURE 47—The McIntyreShotgun Barrel Facing toolconsists of a sharp, rotary fileand interchangeable gaugenylon pilots, operated manual-ly via a brace-and-bit design. Itallows for lathe adaption.
Basic Metalworking and Machine Tool Operation76
Self-Check 7
Indicate whether the following statements are True or False.
_____1. Once you remove some muzzle length from a shotgun barrel, there’s no way torestore choke and the barrel should be trashed.
_____2. A supersharp piloted center drill or a nonthroated reamer ensures that a bore edgeis cleanly trimmed with no burrs or metal rollover whatsoever.
_____3. Forceful polishing can give the muzzle-bore edge rollover, which can affect accuracy.
_____4. A 95 percent unobstructed bullet getaway at the muzzle edge ensures optimumaccuracy.
_____5. The first muzzle-finish priority is to protect the bore edge.
Check your answers with those on page 108.
Basic Metalworking and Machine Tool Operation 77
ADVANCED GUNSMITHINGSKILLS
The Palmgren Milling Attachment for the Lathe
The Palmgren milling attachment bolts onto the lathe’s tool
post and is controlled by the compound and cross feed
(Figure 48). The arrangement often encourages a gunsmith to
purchase a genuine milling machine rather than substituting
for one. It is, however, handy for milling dovetail sight slots
into barrels and ramps, grooving out adjustable forestock
rails for target rifle attachments, and experimenting with
assorted nameless gadgetry (Figure 49).
FIGURE 48—The Palmgrenmilling attachment enabled us to cut this 1/8 inch and 1/4 inch slot for an adjustabletapering lathe gadget.
Years ago, Neil Kenney of Sandpoint, ID, made an adjustable
barrel taper turning attachment on and for my lathe with a
Morse No. 2 taper to fit the tail stock. It consists of a steel
bar with measurements of 11/2 inches � 21/2 inches � 51/2
inches, bored and silver-soldered onto the large end of the
Morse taper. A second identical steel bar 3 inches long was
slotted in from both sides inch wide for a distance of 1/4
inch. Next, a 3/8 inch mill was used to widen and deepen
these slots 1/4 inch or halfway through the bar.
The mill opened the bar slots for the 1/4 inch � 15/16 inch
20 TPI cap screws, which turn into the drilling and tapping
of the first bar affixed to the Morse taper. A 60 degree center
drill cut a center into the remaining solid section of the
grooved bar. The center drill was locked in the three-jaw
lathe chuck. With the forward adjustable steel bar of the
newly made unit centered and the Morse taper in the lathe
tail stock, the 60 degree center was cut using the center drill
in the head stock chuck.
The newly cut center area was then heated dull red with
Kasenit applied and melted several times and quenched at
a dull red for temper.
Basic Metalworking and Machine Tool Operation78
FIGURE 49—Cutting dovetailsight slots is only one taskyou can complete with thisgadget.
Basic Metalworking and Machine Tool Operation 79
The setup provides a left and right adjustable tail stock center
without moving the actual lathe tail stock center. It can be a
fantastic time-saver. A well-lubed steel ball bearing was used
to fit into the barrel center and the center of the newly made
adjustable tail stock center, to be used for taper-turning bar-
rels. After making a portable leveling support from the ways
to the bottom of the taper unit, it worked amazingly well. The
adjustable bar was made using the milling attachment. This
is only one example of what you can do with such a tool
(Figure 50).
Lathe-making a Tap
If necessity is the mother of invention, desire is the father.
I had an extra-new M-69 Winchester .22 L.R. barrel on hand,
and a .22 rifle action that required a new barrel. With them,
my helper Bud and I discovered that the receiver on the rifle
with the damaged barrel was bulky enough to bore out and
thread for the new M-69 barrel.
Experimenting was in order that below-zero winter week. “We
might be able to make the tap on the lathe,” Bud commented.
Shortly, he returned from the machine shop with what he
FIGURE 50—Shown is a head-on view of the tail stock of thelathe-made taper attachment.The lubed ball bearing in thebarrel and the adjustable taperplate hold the barrel at tailstock.
presumed would be suitable bar stock. Bud was a mechanical
whiz on almost anything. He spent years as a millwright and
he had endless in-shop experiences. Initially, he trained me
to operate a lathe. There are many sources of learning. Take
advantage of every one you can.
After turning the steel to 5/8 inch diameter, he threaded it
24 TPI, even working a slight taper onto its end area. The
flute-cutting was slow and tedious without using the milling
machine. Bud ground a lathe bit into a “hook-rake” shape,
and hand-fed the longitudinal passes, advancing the cutter
very slightly for each pass.
The flutes weren’t really of adequate depth and width. This
was an experiment, whereby you always learn something and
do it better and different the next time. The face of the tap
teeth had to be faced with a small tool post grinder, using
one of those thin cutoff wheels and operating on a “touch
system.”
Next, we pursued tempering without an oven—again a gam-
ble. Bud used our shop system of heating dull red, melting
several coats of Kasenit onto the surface, then quenching at
dull red. It took several experimental runs before we got that
“ting and sing” response with a sharp file.
To test the homemade tap before risking a rifle action,
Bud bored a section of cutoff rifle barrel blank to 5/8 inch,
(Figure 51, threaded OK). This is merely an example of what
you can do with machinery and imagination. It has been said
many times that “gunsmiths are the world’s most inventive
people.” Such experiments add an intense interest to your
work.
Basic Metalworking and Machine Tool Operation80
Basic Metalworking and Machine Tool Operation 81
The Milling Machine
Modern gunsmiths should also become aware of the short-
falls of a lathe milling attachment such as the Palmgren.
Those who require a complete milling machine come to realize
it and often consider “busting the budget” to get one. As with
a quality lathe, drill press, and endless small tools, a milling
machine’s uses are endless.
A member of our rifle team needed to standardize the
accessory rails of several target rifles to interchange with
a Feinwerkbaus Model 600, .177 caliber Olympic-type prac-
tice air rifle, his Model 2000 .22 L.R. target rifle, and a
Remington M-37 target rifle. The Feinwerkbaus has a unique,
ultraconvenient adjustable forend stop that unlocks with a
mere quarter counterclockwise turn. It locks tight in any
position with a clockwise quarter-turn anywhere along the
length of the accessory rail. The Feinwerkbaus is fast and
dependable.
Tim Hoechert, an aspiring young shooter and mechanically
inclined gun hobbyist, took measurements from the
Feinwerkbaus. He then picked up a bar of aluminum 3/4
inch wide, 1/4 inch thick, reground a milling bit to do the
FIGURE 51—Shown is the 5/8inch �� TPI threading tap onthe right, (M-69Winchesterbarrel shank specs), made onthe lathe. The arrow points tothe thread in the inch collarof the barrel steel made totest tap.
Basic Metalworking and Machine Tool Operation
job, and provided me with a new accessory rail with two days
to spare. All this cost a fraction of the European cost minus
the long waiting period (Figure 52).
Cutting dovetails for sight installations are mere beginnings.
You can make obsolete sight bases, customize various mech-
anisms, and mill quarter-ribs on barrels. You can remove
excess metal from military
actions such as the bridge of 1917 Enfields, modify pistol
slides for custom sights, plus endless day-to-day needs as
they arise (Figure 53).
Rural and semirural gunsmiths will get calls for making repair
parts for various machines. Many jobs are easy compared to
complicated gunsmithing. Odd jobs will help you survive
through slack seasons until you establish your business.
You’ll need a bit of levity with some customers. For example,
a chap came in looking for a gun part he had broken (on an
obsolete model). When I asked for the broken parts so I
might copy them, he became indignant. “Yuh mean you don’t
remember what it looked like?”
Be patient, have fun! You can also experiment with muzzle
brakes and cutting slots in them. One of our gun-nut friends
has built several 50 caliber, bolt-action rifles. He won’t fire
them without his muzzle brake.
82
FIGURE 52—Shown is a coun-try shop equipped with lathe,milling machine, and weldingoutfits. Tim Hoechert’s gener-al mechanics ability keeps himbusy. Here, he demonstratesthe ease with which you canmill a 3/8 inch sight dovetail(to be followed with slightdovetail file cleanup fittingwork).
Basic Metalworking and Machine Tool Operation 83
Welding Requirements
In average gunsmithing, welding different style knobs low
enough on bolt handles to clear scopes (including the large
eye-piece optics) is probably the largest material you’ll work
with. I personally detest the idea of cutting off military bolt
handles and welding on fancy-appearing substitutes. I just
can’t see applying all that severe heat so close to the bolt
body and cocking cam area.
Suppose a customer desires a spoon-shaped, knurled knob,
or any other decorative style. My theory is to forge the bolt
safely heat-wise to begin with, and then to cut it off about
one third or midway out from the bolt body. Then, weld on
the new knob in a manner that heat-protects the cocking
cam and prevents heat runs toward the critical locking lugs.
Caution: It’s imperative that you have some gas welding
experience before working on costly parts and/or parts that
you can’t replace. I advise a complete welding course.
If you can’t afford a complete course, most professional
welders can show you the ropes and give you a grand start
if you’re serious and pay attention. Attempt to actually work
with a professional in an apprenticeship for a while. You can
FIGURE 53—Shown left toright are collets: 3/8 inchdovetail, sight-slot cutter,large dovetail cutter, and fourmilling bits (a small portion ofmilling tools the machine canutilize).
learn the basics rapidly. Then, you can practice by yourself,
realize when you’re right or wrong, and make corrections
accordingly.
My instructor wouldn’t quit telling me over and over about
the ultra-importance of having that parent metal puddled
(melted) before adding melted welding rod metal. The parent
metal, usually being larger than the welding rod, takes more
heat and time to melt. Keep the welding rod in the bottom of
the parent metal puddle. Raise the rod and draw back the
flame if the puddle gets too big. These actions and reactions
must be fast, yet under control. Practice is the answer.
Caution: Usually, the beginning welder’s biggest error is
attempting to add melted welding rod to a heavier parent
metal that’s not yet in the melted stage. Beware of this!
Gunsmith welding is usually on small parts. You’ll need to
practice with a small welding tip, 1/16 inch rod, or taper-
ground smaller yet. When welding small, thin parent metals,
it’s a critical matter of mating flame, rod, and parent metal.
It requires fast application of rod at the flow stage and a fast
getaway to avoid damage to the delicate part.
Many small welding jobs are merely to correct worn parts’
buildup or to rejoin broken parts. You must remove excess
weld metal if it interferes with functioning. However, if no
interference exists, merely partially smooth your weld. Extra
dimension adds strength.
Tempering and/or Case-hardening
You can often improve buildups on gun parts’ wear surfaces
by tempering and/or case-hardening. Heat the part dull red,
dip it into Kasenit hardening powder, apply a torch to melt
in the chemical, dip into powder, and melt two more times.
Then, when it reaches dull cherry red, dip it into cool water.
This usually gives a long-wearing ultrahard surface, yet the
inner metal isn’t breakage-hard.
Years ago, my shop did many M-94 Winchester Link nose
buildups on part number 4694X Link. The front end of this,
which I call the link nose, controls the retention and entry of
the next round of ammunition into the action above the car-
rier. The carrier angles upward at lever opening completion
Basic Metalworking and Machine Tool Operation84
Basic Metalworking and Machine Tool Operation 85
and lines the round up for chamber entry upon lever closure.
These link noses were soft steel, wore easily in fairly new
rifles, and sometimes permitted a cartridge to pop back
under the carrier and hopelessly inactivate the rifle. This
made the rifle useless even as a single shot!
My years-ago grizzly bear guide in Canada admitted he
bloody-well had to dig “euwt” shells with a nail now and then
(not to my liking as a guide’s backup rifle). I managed to get
his .30–30 M-94 Winchester into my shop and correct this
along with adding a new barrel and other necessary parts.
Dozens of these link nose buildups and hardening jobs hap-
pened during the heyday of my in-town shop. I became so
familiar with it that I no longer needed to measure the link
nose, only glance at it after the weld-up and grind-down, then
Kasenit it. Not one of these repairs ever came back. The new
hardness stopped all wear. Too bad the factory couldn’t have
done this originally, but it leaves endless work for upcoming
gunsmiths, if you pursue it. This is just one worthwhile
example of what welding buildup and Kasenit hardening
can do.
Hardening surfacing with a welding rod is also a possibility.
A welding supply business can provide you with all pertinent
information. Most gun parts are too small for this applica-
tion, but keep it in mind. If you’re going to become a welder,
you’ll be repairing many parts besides guns. Gun shops often
accept assorted repair work. It’s beans in the pot and another
payment on the lathe and equipment.
Note: You may require separate instruction/learning on elec-
tric (arc) welding. It’s usually less applicable to gunsmithing
than the acetylene oxygen welding setup, but pass up
no learning opportunity. You’ll discover places to use it
beneficially.
Welding Instruction Books
The number of publications available for learning about
welding is surprising. As a gunsmith, forget the heavy-duty
bulldozer and horse-drawn grain binder bull-wheel repair
instructions. Stick to the delicate and fine points of the gun-
smithing trade. However, read and study all the books you
can. Opinions and methods differ, but gunsmithing school
intelligence will guide you as your experience broadens.
Soft-soldering vs Silver Soldering
Some claim silver solder to be as strong as anything it will
bond with. Steel must be heated nearly red and fluxed in
order for it to flow and take. Surfaces must be clean. Silver
soldering is used often on parts joining and repairs not relat-
ed to the rifle’s action or barrel, as the extreme heat required
can change tempers and become detrimental, even dangerous.
Installing front sight ramps with silver solder is a “no-no” in
our shop!
Brownell’s Force 44 soft solder is easy to use with Blitz sol-
dering flux. When the adjoining barrel area is covered with
talc crayon, the solder won’t run. Any slight edge-over can be
sanded off before bluing, and the solder survives the blueing
in-tanks treatment. It’s strong, and we’ve had no failures. Its
low-temperature melting is extremely desirable, which makes
it easy to use by novices as well as professionals.
Front Sight Installation
It’s just as easy to install front sights correctly as it is to
“goof ‘em.” I’ve seen many front sight ramp installations done
with induction brazing or silver solder. It takes severe heat to
remove them. Likewise, original installation called for similar
temperatures, which can be detrimental to barrel and action
steels, temper retention.
Ordinary soft solders of the past failed to hold up under
“tank-bluing” chemicals such as Oxynate #7, BLU-BLAK,
and others. They didn’t hold up unless a dangerous cyanide
additive was used as well as low temperature control, which
required much ventilation. Silver-bearing Force 44 soft solder
melts, flows, and adheres easily to clean steel surfaces. Place
the barrel in a padded vise, align it vertically as close as pos-
sible with the action, and place the ramp on the top front of
the barrel in the desired location. Do your best to get it accu-
rately on top. Then, use a sharp, metal scribe to mark out its
outline, and remove and gently sand off any bluing ruse or
Basic Metalworking and Machine Tool Operation86
Basic Metalworking and Machine Tool Operation 87
discoloration from the ramp affixing area. Next, with a Talc
crayon, coat the barrel area surrounding the proposed ramp
position. Use a heated soldering iron or unit to melt Force 44
soft solder onto this fenced-off part of the barrel front.
Note: At the same time, you should have the steel ramp fixed
in a vise bottom-up with a cleaned surface. Apply Blitz solder-
ing flux and Force 44 as you’re doing to the installation sight.
Don’t forget the flux, and don’t overdo the application. It only
takes a good surface coating, not any form of pileup solder.
How do you get the ramp exactly on top? Considering the
position of the barreled action in the stock, the manner in
which a shooter might hold it (yet still claim level) makes it
difficult. However, the mechanical level must prevail. There
are level-seeking devices such as B-Square’s Cross-Hair
Square that work from the flats of the bolt-way’s lugs milling.
Nothing I know of could be more accurate.
However, a ramp front sight’s response isn’t as easy. The
shooting eyes must also play a part. After the barrel surface
and the underside of the ramp are tinned (light coating of
solder on the surfaces), position the ramp on the barrel as
level as possible. Then, place a balanced weight hanger over
the ramp, and apply moderate heat with your propane or
acetylene torch, only enough to melt the solder (Figure 54).
You’ll see the ramp settle snugly onto the barrel. Unless you’ve
overdone the tinning solder applications, only the tiniest
amount will ooze out from under the ramp. Pull the heat
temporarily and make a fast visual inspection for vertical
and horizontal alignment. While the solder is still fluid, you
can gently tap the ramp left or right.
You must make a final check after the solder sets up. Place
the barrel and action into its stock and assume different
shooting positions.
Doing so will help you determine whether you have a 12 to 6
o’clock lineup. If not, reheat the barrel and ramp area and
gently tap the ramp as needed to line it up.
The ramp installation system also works well with open, rear-
sight “higher station ramps.” Furthermore, European-type,
to-barrel formfitted front sling swivel pads can be soldered
in this system without concern about failures.
The shop-devised three pound weight hanger ramp holder
works fine; however, you might prefer an Erhardt spring-
loaded sight soldering jig or other clamp-type fixtures.
Parts-holding at the Workbenches
Vises at every workbench are often not enough (Figure 55).
Additional gadgetry such as the large “Octopus” with four
adjustable ball joints, and the “Mini-Octa Holding Tool” save
a lot of time and enable you to do better work on odd-shaped
parts.
Basic Metalworking and Machine Tool Operation88
FIGURE 54—This no-cost, 3 pound balance weightdevised in the shop brings the ramp snugly to the barrelwhen solder-tinned surfacesmelt. Adjustment for left-rightvertical lineup is easy whilehot.
Basic Metalworking and Machine Tool Operation 89
Thinking gunsmiths can also come up with endless ways to
hold gun parts (Figure 56). On my list are wooden clothes-
pins, rubber bands, masking and electricians’ tape, three-
minute epoxy, and rubberized glue. All of these are easy to
remove after their usefulness is over.
I’ve used the compound vise on the Delta drill press, as it
swings, lowers, and elevates. You can line it up with any
round part being held in the drill press chuck by using a “V”
block to align it. This can be worked out quite similar to the
head stock and tail stocks in the lathe (although the lathe
setup is faster and better).
FIGURE 55—Shown are fourside-swinging adjustable balljoints, and two grafted-on visegrips. This 14 inch high,Octopus holding tool is adandy for welding and soft orsilver soldering.
Many gunsmiths find that photography advertises and sells
their wares. Clutter in the foreground, background, and
elsewhere is difficult to eliminate in a busy shop full of
equipment.
Our swinging drill press table with compound vise saved the
day for many of the photos shown in this unit. I locked up
a 21/2 foot length of 11/2 inch square wood to 11/2 by 11/2.
Doing so, I was able to bring the position of the items out to
the side where we could provide white, gray, or black back-
drops, as well as making proper lighting possible. For some
work, we used thinner pieces of wood material.
We used the methods just mentioned to hold items in place.
At one point, three vise grips were hooked onto each other,
plus clothespins and metal clipboard clamps (which will often
work to hold small parts for soldering or welding). After some
time, toying with ways to hold parts creates ideas your mind.
With some thought, you’ll be able to devise ways of holding
almost anything where and how you want it.
Basic Metalworking and Machine Tool Operation90
FIGURE 56—The Mini-Octa-Holding tool weighs one poundwith base, has less adjust-ment, but can hold in positionbroken small parts for weld-starting or silver-solder repair.It’s shown here gripping an M-94 Winchester carrier.
Basic Metalworking and Machine Tool Operation 91
Joining Two Firing Pins
Admittedly, there’s no substitute for correcting a broken fir-
ing pin by installing the proper new one. However, at times
(like in distant locations) a new part may not be available.
Fortunately, firing pins, often a fairly breakable part, can
likewise be made by gunsmiths with a lathe and basic equip-
ment. The work may require additional charges, but you
can keep your customer satisfied. Figure 57 shows a broken
M-94 Winchester firing pin with its rear end in the head
stock lathe chuck. The front broken point end has been
removed with a bench grinder cutoff wheel, as has been the
front section of a second broken M-94 Winchester firing pin,
being held in smaller tailstock chuck. Both ends have been
“V” ground for welding together easily and completely.
When actually welding, shield your chucks and lathe ways. I
only partially weld such lineups in the lathe to prevent the
possibility of heat damage to costly equipment. You can
remove the unit and finish the welding while it’s being held
in a regular workbench vise. After this, partly grind off the
welded surface and then return it to the lathe to obtain a
perfect final diameter. The cutoff wheel will remove the extra
length of the long end, and you can commence the tedious
task of copying the original dimensions.
FIGURE 57—Welding or silversoldering two round pins,parts, or screws together in perfect alignment is bestdone between lathe headstock and tail stock. Shieldchucks and ways during actualwelding. Only start your weldin the lathe. We omitted theshielding for the chucks forphotography reasons.
Someone will ask, “Why copy a firing pin if you have one to
copy from?” We don’t have one to copy. M-94 firing pins
almost always break at the tip beyond the major curve-down
from body diameter. You can always check tip size against
the firing pin opening in the bolt face. Since in this instance
we welded together two M-94 firing pins, you would be dealing
with metal too hard to turn in the lathe properly. You could
anneal it or use a tool post grinder to shape it.
Better yet, if and when you make this type of weld-on exten-
sion to form a M-94 firing pinpoint, use a drill rod. It’s usually
tough enough to do well without tempering tinkering.
Basic Metalworking and Machine Tool Operation92
Basic Metalworking and Machine Tool Operation 93
Self-Check 8
Fill in the blanks in the following statements.
1. You can improve the wear surfaces of gun parts by _______ and/or _______.
2. The Palmgren milling attachment bolts onto the tool post to be controlled by the _______and _______ .
3. Before you weld expensive parts or those hard to replace, you should get some _______.
4. Welding on different style _______ low enough to clear scopes is probably the most oftenpracticed welding task in average gunsmithing.
5. The Palmgren milling attachment is handy for milling _______ into barrels and ramps.
Check your answers with those on page 108.
BUILDING YOUR OWN EQUIPMENT
Gunsmiths of yore made many of their own tools. However, it
takes some equipment and tools to make more tools. It also
takes a lot of time and energy that you can afford to expend
only if the end result is compensatory to the other side of the
ledger. All the gunsmithing skill in the world doesn’t help if
you have improper tools, no tools, and/or you’re unable to
procure or make them. Experiencing the art of making some
of your own tools and equipment is in itself practical gun-
smithing experience. Don’t let any ingenious ideas die on
the vine.
When everyone in the shop is busy, it’s impractical to take
time out to experiment and devise new tools. Besides, most
needs are available from gunsmiths’ supply houses such as
Brownells and B-Square. However, you’ll have slack time.
In fact, vigorous young (and old) gunsmiths with intense
interest and enthusiasm make spare time to bring ideas
into creation.
Building a Glass Bead Blasting Cabinet
Glass bead blasting cabinets are available in many sizes and
forms at various prices. With welding expertise (every gun-
smith should take a good course in welding), you can study
the various patterns and build your own cabinet. This will
save you money and add to your welding experience. My pre-
liminary welding instruction came from a bulldozer and logger-
truck mechanic. However, he took great pride in doing the
tender things also, frequently demonstrating running a bead
across a Prince Albert tobacco can using a 1/8 inch diameter
welding rod. You’ll need to acquire the technique of handling
tender welding jobs. It takes practice and intense interest
and desire. Gunsmithing also requires acetylene equipment.
Building your blasting cabinet is an ordinary welding job,
one that you’ll probably best handle with an electric welder.
Formulate a plan covering dimensions, so you can cut each
steel plate cut accordingly. You cut the two-arm working
Basic Metalworking and Machine Tool Operation94
Basic Metalworking and Machine Tool Operation 95
holes into the cabinet with an acetylene cutting torch, as well
as the working view window on the top hinged cover 24 inches
� 45 inches. The view window in Figure 58 measures 8 inches
� 1/2 inch and is too small. It should be enlarged by about
25 percent. The top of the swinging door is full-width-hinged,
the underside lined with a “refrigerator door” type sealing
cushioning material to contain all dust.
The gadgetry on the right side of the cabinet is a canister-
type moisture collector (a must), inside light fixture, and
switch. Without the moisture collector, your metal will be
moisture-scarred.
The measurements of the cabinet are as follows.
• The depth of the front flat face of the cabinet where the
working arm holes are is 71/2 inches.
• From there to the bottom of cabinet “V” is 10 inches.
• From the “V” to the upward angle is 20 inches.
• Then it’s 12 inches vertically to meet the back side
hinged top door.
FIGURE 58—Shown is a blastingcabinet with a full-size top door24 inches �� 45 inches, which is adequate for most barreledactions, including shotguns. Theview window should be larger.Most 36 inch wide blasting cab-inets, commercially available,could be inconveniently small.Study your purchases.
The left side of the cabinet has identical dimensions but
without accessory cut-ins. A large, centrally located handle
is affixed to the lower edge of the swinging opening door.
At the bottom of the “V” cabinet, you’ll need about a 421/2
inch exit pipe, trimmed flush and smooth inside the cabinet.
The pipe makes brushing out all the old worn-out glass
beads from time to time an easy task. Have a bucket placed
on a shelf under the drain spout to catch all the worn beads.
The front legs of this cabinet are 38 inches high; the rear legs
inches high. Steel crossbars measuring 1 inch by 20 inches
are a square, channel-hollow steel material. They were weld-
ed onto the front and rear legs at 10 inches from the bottom
on both the right and left sides of the frame. To add rigidity
to the leg frame, a similar bar was welded onto the rear left
and right legs, 43 inches span. To stiffen the frame even
more, another 1 inch bar was welded into place from the
lower left, 10 inches above the bottom brace cross section
and upward at an angle to join onto the top of the right rear
leg. This steel frame provides room for shelf boards to hold
extra glass beads, gloves, and the bucket under the drain
spout. You’ll need to make an almost airtight plug to seal
the inside of your drain spout. I made mine with wood and
a cloth cover thumped into place with a hammer.
Warning: Don’t forget to cut about a 6 inch hole into the
back side of the blasting cabinet and install and completely
seal a plastic pipe to the outdoors or dust receiving area.
During the initial excitement of our success, neither my
helper nor I remembered the need for an exhaust pipe. The
initial tryout created a mushroom cloud of glass bead dust
forced out by the blast gun along the door edges into the
shop.
Another important addition is to affix a frame over the inside
of the cabinet door view window. Cover this with clear plastic
that can be replaced easier than installing new window glass.
Battering from the glass beads under pressure soon dulls
both window glass and plastic.
To prevent wear on the steel body material, the inside of this
cabinet was completely covered with a heavy doormat of
rubberized smooth material. The arm holes consist of long
gauntlet rubber gloves with sealed rear edges and strips of
Basic Metalworking and Machine Tool Operation96
Basic Metalworking and Machine Tool Operation 97
foam cushion-type material about inch thick and inch wide,
sealed with rubber cement. The sloped back of the cabinet
provides easy reach. The width accommodates long barreled
actions, such as M-97 shotguns, long-barreled rifles, and
other surprises. The slight extra size of the cabinet doesn’t
cost extra.
A wooden “L” frame holds the position and keeps barrels,
actions, and barreled actions off the cabinet bottom and in
position to glass bead blast. The frame is 11/2 � 11/2 � 20
inches in length and two 7 inch pieces of the same material,
strapped together by two thin wood slats. There are three
wooden pegs installed in each long section of the “L” frame.
This provides spacing for better bead blasting. Use a soft
wood such as cedar for the suspension frame. This also
minimizes finish marring.
There are numerous plans, designs, shapes, and sizes of
blasting cabinets, many available commercially. Regardless,
it makes good sense to build your own. Then you can provide
yourself with the features most desirable to you. You should
consider some of the aforementioned points of size, view
window size, and protection from blasting erosion with the
clear plastic. Don’t forget the moisture-collecting gadget.
When purchasing glass beads, there’s little reason to buy
the fine size. The beads wear “fine” quite rapidly.
Warning: When using the blaster, wear a good respirator
and observe the warnings on the canister container bucket.
Also, always wear eye protection. Avoid dusts and vapors
from all types of products. In my shop, we cover the front of
our respirators with a heavy, fuzzy flannel cloth, held over
the screw-on filter cap with a tight rubber band. This precau-
tion is simple, yet effective. It’s surprising how much “crud”
you’ll rinse out of this cloth, and you’ll also add to the filter
life—as well as your own. Metals, grinders, buffers, hand
electric tools, even sanding a gun stock, all create dusts.
You should protect yourself from it.
Plans for a Belt Sander
Jack McIntyre holds a diploma from International
Correspondence Schools. His own shop-made small belt
sander wasn’t super-costly in the beginning (Figure 59).
Any go-getter can build a similar one, as well as the barrel-
holding cradle, with turning centers.
Among his other gadgets is a “V” flat spring swaging pliers
alteration that saves time and places the “V” where you want
it. It also works on round spring stock.
Note: Following are the actual plans for building the belt
sander pictured in Figure 59. Jack McIntyre provided the
plans with his compliments. After 15 years of use, the sander
is still performing better than most store-bought models.
Read the instructions all the way through and study the
drawings that follow them before you start. Make the parts
one at a time, and carefully follow the instructions.
Fitting the bearings is the only critical measurement in the
entire sander. You’ll notice the word “approximately” used
a lot. Substitutions such as the size of pipe and most other
parts are OK.
Basic Metalworking and Machine Tool Operation98
FIGURE 59—Gunsmith JackMcIntyre built this simple, yet efficient belt sander andbetween-centers barrel-holdingcradle. You can build a similarone.
Basic Metalworking and Machine Tool Operation 99
Making the Sander
The suggested parts list is as follows.
• 34 inches of 1 inch black steel pipe
• 1 each 4.000 diameter � 1.000 floor flange
• 1 each 11/2 inches double-strength pipe, 4 inches long—
or 2 inches round cold rolled steel rod
• 12 inches of 3/4 inch square steel, cold rolled
• 11/4 inches 11/4 inches � 3 inches cold rolled steel
• 3 inches � 3 inches � 1 inch cold rolled steel
• 2 each 203 sealed bearings
• 2 each 202 sealed bearings
• 1 Volkswagen valve spring (or whatever else you have, or
can get) for a belt tension spring
• 2 inch pulley
Note: We didn’t list miscellaneous screws. You’ll see them in
the drawings.
Figure 60 illustrates the first stage of the belt sander. Take
11/2 inch, double-strength, 4 inch long pipe and bore out
both ends to 1.5730 diameter 500 deep. This is for the 203
bearings to fit in (part A in Figure 60). You can use a piece of
2 inch round cold rolled steel for this part. After boring it
out, place it aside and go to next step.
Basic Metalworking and Machine Tool Operation100
FIGURE 60—The First Steps ofthe Sander
Basic Metalworking and Machine Tool Operation 101
Make Shaft A from an 8 inch piece of 3/4 inch cold rolled
steel. Figure 61 shows the detail of Shaft A in the upper
right-hand corner. Place Part A aside and continue to the
next step.
You can make Wheel #1, also in Figure 61, from wood, lami-
nate, or any other substance you want. I used a wheel out of
a textile mill 6 inches � 2 inches. It was, at one time, on a
hand truck of some sort. It should have a rubber covering. A
2 1/2 inch length of inner tube makes a fine cover. Nu-Matic
Grinders, Inc., Cleveland, OH, sells an inflatable grinding
wheel, which also would be excellent here. However, it does
cost $75, and the price may have risen since I last checked.
Put aside these parts and don’t try to assemble anything yet.
Cut 30 inches of 1 inch pipe to make Pipe C (Figure 60).
Thread and screw it tightly into the floor flange.
Cut 33/4 inches of 1 inch pipe for Pipe B.
FIGURE 61—The Second Steps of the Sander
Grind one end to fit the contour of Pipe C. Grind the other
end to fit the 11/2 inch Pipe A.
Weld Pipe B square to the center of Pipe A. Position the other
end approximately 6–7 inches from flange end of Pipe C and
weld it, making sure it’s all square before you weld.
Assembly A. Make Wheel #2 21/2 inches � 2 inches thick
as indicated in (Figure 62). You can make Wheel #2, like
Wheel #1, out of practically anything as long as it has a rub-
ber cover and a crown. In case you’re uncertain about what
I mean by a crown, it has a larger diameter in the center than
on the outside edges. Approximately 1/8 inch will be fine; it
doesn’t have to be exact. See Figure 62 for the miscellaneous
parts and instructions for this wheel assembly.
Basic Metalworking and Machine Tool Operation102
FIGURE 62—A Full Drawing of the Sander
Basic Metalworking and Machine Tool Operation 103
Part B. For the shaft, take a piece of cold rolled steel, 3/4 �3/4 � 6 long, and turn one end down round as shown in the
drawings. Thread as shown, but don’t bore the hole at this
time. Put this aside for now.
Parts C and D. Take one 3 inch � 3 inch, 1 inch cold rolled
steel to make parts C and D. Drill a 15/16 inch hole 1 inch
from one side, which will eventually be Part D after you split
it. Next, drill two holes, 1/4 � 2 inches deep, then ream these
two holes out to 0.344 � only 1 inch deep, as shown in
Figure 62. Saw the part in two pieces at the center of the
1 5/16 inch hole. Now it looks more like the drawings. Cut
the notch in Part C according to measurements shown in
Figure 62. Drill holes through on the sides 0.375 inch diame-
ter as shown, tap holes as shown, and place them aside.
Part E. Cut 1.375 length of 3/4 inch round and drill a inch
hole through the center.
Part F. Cut 3 inches of 3/4 inch � 3/4 inch square steel.
Contour one end to fit Part E, as shown.
Part G. Cut a 3 inch length of 11/8 inch (or 11/4 inch)
square steel. Mill it out as shown in Figure 62. You can also
fabricate this part out of 3/16 inch or 1/4 inch plate steel,
whichever is easiest and cheapest for you.
Now, weld Parts E, F, and G together, as shown in Figure 62.
Then, drill and tap holes in G, also as shown in the drawings.
Part H. Cut two pieces of steel 1/4 inch � 3/4 inch � 21/2
inch. Weld one on the bottom of Part F and one on the bot-
tom of Part C. Drill and tap Part H 1/4 inch–20 (Figure 62).
These screws are only to keep the spring from falling off. This
was the way I did it. (You may think of a better way.)
Assembly of Parts
Examine Figure 63 carefully before you start, especially the
assembly of Shaft A (Figure 61), Pipe A (Figure 60), and the
bearings. Study the drawings carefully, and get all the neces-
sary parts for this assembly. Put Shaft A through Pipe A, put
a bearing on each end, and press the bearings inside the
pipe and onto the shaft.
Note: Both bearings are pressed inside at the same time.
Install Wheel #1. Install the pulley as in Figure 61.
Install Parts C and D. As shown in Figure 63, install parts
C and D around the pipe, but down close to Wheel A. This
assembly is here temporarily—until the positioning of the
wheels is complete. Then, you’ll move it up to the correct
position.
Install E, F, and G Assembly. This attaches to Part C with
a 3/8″ � 3 inch steel dowel, as shown in Figure 63.
Basic Metalworking and Machine Tool Operation104
FIGURE 63—Assembly Drawingof the Belt Sander
Basic Metalworking and Machine Tool Operation 105
Installation of Wheel #2 on Part B. Figure 62 shows the
assembly procedures.
Next, put Part B (refer to Figures 62 and 63) into the milled
slot in Part G with a temporary space fitted into the top of
Part G. This will fill up the slot so that when you drill the
hole in Part B, it will be in the correct position. The hole is
already drilled in Part G. After drilling the hole in Part B,
remove the temporary spacer. Part B will then have the nec-
essary pivot up and down for tracking the belt. The tracking
screw goes in the top, as shown in the assembly drawing.
Now, install the Belt Tension Spring. After doing so, you can
raise Wheel #2 to its correct position, which is determined by
the length of your sanding belt. You can use up to a 54 inch
belt with this length pipe. To use a longer belt, you need a
longer pipe. I use a 2 inch � 48 inch belt.
Use a motor approximately 1/2 or 1/3 horsepower, 1725 rpm,
with approximately a 3 inch pulley. You can mount this
motor on the sander at the most convenient place for you,
either underneath or behind. Sometime you can find this
type of motor at most flea markets for a low price. They’re on
washing machines, dryers, etc. Or, you can buy a new one.
Basic Metalworking and Machine Tool Operation106
Self-Check 9
Indicate whether the following statements are True or False.
_____ 1. Experiencing the art of making some of your own tools and equipment is in itselfpractical gunsmithing experience.
_____ 2. If a glass bead blasting cabinet doesn’t contain a moisture collector, the metal thatis glass blasted will be moisture-scarred.
_____ 3. It’s not necessary to exhaust vent a glass bead blasting cabinet, as the cabinetitself is sealed and no dust can escape.
_____ 4. In the belt sander plans, fitting the bearings is the only critical measurement in theentire plan.
_____ 5. You should make the walls of a good glass bead blasting cabinet out of oak.
Check your answers with those on page 109.
107
Self-Check 1
1. False. They break easily.
2. True
3. False. You can start a thread with a new taper tap.
4. True
5. True
Self-Check 2
1. flare
2. shim pack
3. wire brush
4. bore-sighting
5. left, right
Self-Check 3
1. False. You should retract the torch flame gradually.
2. True
3. False. Altering bolts takes experience and practice to
master.
4. True
5. True
Self-Check 4
1. Emery stones
2. felt-gritted bob
3. extractor claws
4. insufficient tension
5. loaded cartridge
An
sw
er
sA
ns
we
rs
Self-Check Answers108
Self-Check 5
1. True
2. False. It can be about 0.003 inch larger.
3. True
4. False. The chrome-moly demonstrates a gilt-edge
accuracy loss quicker than the stainless steel.
5. True
Self-Check 6
1. tool post grinder
2. 0.063 inch, 0.065 inch
3. Tempilaq
4. nickel steel
5. fatigue-proof
Self-Check 7
1 False. You can restore the muzzle by installing adapter
tubes or by using a B-Square swaging tool to work a
choke into it.
2. True
3. True
4. False. Only 100 percent provides accuracy.
5. True
Self-Check 8
1. tempering, case hardening
2. compound, cross feed
3. gas welding experience
4. knob bolt handles
5. dovetail sight slots
Self-Check Answers 109
Self-Check 9
1. True
2. True
3. False. Install an exhaust pipe from the cabinet to the
outdoors or dust receiving area.
4. True
5. False. The walls of the blasting cabinet are made of
steel.
Self-Check Answers110
NOTES
111
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Basic Metalwork and Machine Tool Operation
When you feel confident that you have mastered the material in this study unit, complete the following examination. Then submitonly your answers to the school for grading, using one of the exam-ination answer options described in your “Test Materials” envelope.Send your answers for this examination as soon as you complete it.Do not wait until another examination is ready.
Questions 1–20: Select the one best answer to each question.
1. You can use a lathe for all of the following applications except
A. threading barrels.B. making firing pins.C. mounting recoil pads.D. opening bolt faces for larger cartridges.
2. What type of wheels would you use to achieve a much smootherfinish with an effective contouring capability after an approximategrind-down of a welded repair?
A. Felt 50, 120 grit C. Felt 340, 450 gritB. Felt 150, 240 grit D. Felt 500, 600 grit
3. The best barrel sleeves are made of
A. hardwood. C. steel.B. bullet lead and bearing babbit. D. lead.
EXAMINATION NUMBER:
Whichever method you use in submitting your examanswers to the school, you must use the number above.
For the quickest test results, go to http://www.takeexamsonline.com
Ex
am
ina
tion
Ex
am
ina
tion
02530600
Examination112
4. When soft-soldering a front sight ramp, cover the adjoining area with _______ so the solder won’t run.
A. talc crayon C. TempilaqB. barrel grease D. flux
5. When forging/shaping a bolt, it’s best to use
A. an 8 ounce ball peen hammer. C. a 12 ounce carpenter’s hammer.B. a 10 ounce brass hammer. D. a 1 pound wooden mallet.
6. Prior to drilling and tapping military barrel actions, it’s always preferable to
A. heat the entire receiver ring area.B. coat the receiver with abrasive compound.C. remove the barrel from the action.D. anneal the barrel area.
7. The muzzle type most often used on factory and hunting weight arms is the
A. step-down crown. C. 60 degree center relief.B. crescent moon. D. 72 degree center stylus.
8. When jeweling, the drill press is run at
A. low speedB. medium speed.C. high speed.D. different speeds during different parts of the process.
9. The beginning welder’s biggest error is usually
A. selecting the wrong size welding tip for the job.B. leaving excess metal on the weld.C. adding melted welding rod to a heavier parent metal that’s not yet in the melted stage.D. selecting the wrong type of welding rod.
10. A small, effective center punch used to start drill holes for the most popular scope basescan be made from a broken super-hard
A. 10 drill. C. 25 drill.B. 17 drill. D. 31 drill.
11. Whether using a parallel clamp, calipers, or an elaborate drilling jig, for accurate hole location and drilling you should do all of the following except
A. concave spot grind. C. rescribe several times.B. scribe. D. center punch the steel.
Examination 113
12. Due to slight internal muzzle damage possibilities during manufacturers’ turning of barrelblanks, you should cut about _______ from the muzzle prior to chambering.
A. 1/4 inch C. 11/2 inchesB. 1/2 inch D. 4 inches
13. Fine-cut chisels respond to a delicate application of buffing wheels with grits of _______and down to rouge, provided you learn how to hold them for proper angle and tension.
A. 150–200 C. 350–400B. 250–300 D. 450–500
14. Surfaces heat treated with Tempilaq should be quenched in a(n) _______ percent brinesolution.
A. 2 C. 8B. 4 D. 16
15. Most scope-mounting mistakes of would-be gunsmiths are caused by
A. ignoring the instructions. C. inferior scope mounts.B. lack of quality tools. D. excessive metal finishing.
16. Military conversions most often suffer from
A. inadequate barrel length. C. cartridge feeding problems.B. faulty safety mechanisms. D. too much trigger pull.
17. Fine jeweling is dependent upon all of the following except which one?
A. The base polish C. Fixture indexingB. Your manipulation of the drill press D. The type of wire brush you use
18. It’s best to mount a barrel vise
A. to a lathe. C. to a wooden bench.B. to a shop’s side wall. D. on a concrete pillar
19. Parts that must be heat-treated to unusual depths of hardness must be heated from
A. 650 to 800° F. C. 1,250 to 1,400° F.B. 950 to 1,100° F. D. 1,450 to 1,600° F.
20. When scope body metals are forcibly held in a bind, this condition is referred to as
A. scope strain. C. scope warp.B. pressure pointing. D. scope inertia.
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