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BUILDING A BLOCK II CARBINE

TECHNICAL MANUAL

Technical Writing ENC-2210

William James Abercrombie

12/08/2013

** Check with all local & federal law before attempting any modification to any firearm**

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Chapters Page

I. INTRODUCTION

A. Description of a Block II Carbine 3

B. Purpose of this Manual 3

C. Estimated Time Required to Complete 3

II. PROCESS

A. Tools Required 4-5

1. Hammers, Punches, Screwdrivers, Torque Wrench

2. Vise, Wood Blocks, Safety Glasses

3. Reference Manuals

B. Lower Receiver Assembly 6-8

1. Rear Sling Mount

2. Improved Buttstock

3. Ambidextrous Safety

C. Upper Receiver Assembly 9-13

1. SOCOM Profile Barrel

2. Gas Block / Tube

3. Rail Interface System

4. Flash Hider

D. Accoutrements 14-16

1. Front & Rear Back-Up Iron Sights

2. Day Optic

3. Forward Sling Mount

4. Gun Light / Pressure Switch/ IR Illuminator

III. PARTS LIST

A. Approved Components 17-18

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INTRODUCTION

A. Description of a Block II Carbine

The Block II Carbine is the latest in the M16/M4 weapon series available to

Special Operations Forces. Featuring a free-floated heavy barrel with detachable

sound suppressor, ambidextrous selector lever, visible and infrared illuminators,

and a color scheme not found on conventional military weapons, the Block II

Carbine brings the level of capability and effectiveness to the weapon’s highest

point yet.

B. Purpose of this Manual

This manual will show interested parties the step by step procedure of creating

an accurate copy of the latest M16/M4 series weapon system known as the

Block II Carbine. If properly followed, this manual will enable an individual to

produce as accurate a clone as possible to the Block II.

C. Estimated Time Required to Complete

Time to complete the process outlined in this manual is approximately 1-2 hours

depending on skill level and familiarity. If at any time the procedure outlined

cannot be completed please consult a qualified armorer or gunsmith.

End of Introduction

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PROCESS

NOTE: Weapon must be field stripped and rendered safe and unloaded in accordance

with Training Manual 9-1005-319-10, June 2010 prior to proceeding with Block II

Carbine transition.

Note: Steps in italics are for consumer manual only and not necessary for Colt Defense

personnel. These steps are shown for instructional purposes.

Note: The particular Colt Defense Model 6920 is dated approx. October 2012 and the

accompanying accessories are subject to change.

A. Tools Required

1. Hand and Shop Tools

Brass Hammer (3oz.)

Hammer (approx. 12oz.)

Brass Punches (1/16) (5/64) (3/32) (1/8)

Hex Keys (3/32) (7/64) (5/32)

Torx Key (T15)

Slot Screwdriver (6”)

Armorer’s Wrench

Receiver Action Block

Torque Wrench (1/2” Drive) Not Shown

Bench Vise (6”) Not Shown

Wood Blocks (to prevent marring) Not Shown

Safety Glasses Not Shown

Gloves (optional) Not Shown

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2. Reference Manuals

M16/M4 Series Technical Manual

M16/M4 Series Training Manual

M3X Tactical Illuminator Operator’s Manual

AN/PEQ-15 Operator’s Manual

QD-NT4 Operator’s Manual

SpecterDR Operator’s Manual

Rail interface System (RIS) II Technical Manual

End of Step A

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B. Lower Receiver Assembly

NOTE: Weapon must be field stripped and rendered safe and unloaded in accordance

with Training Manual 9-1005-319-10, June 2010 prior to proceeding with Block II

Carbine transition.

1. Rear Sling Mount

a. Place lower receiver assembly into vise held in place with two wood blocks to

prevent marring.

b. Loosen Receiver End Plate Nut using Stock Wrench and unscrew Buffer Tube

counter-clockwise and remove from Lower Receiver.

NOTE: Care must be taken to prevent loss of takedown detent and spring, during

removal of Receiver End Plate. During removal of Buffer Tube, hold thumb over the

buffer detent and spring to prevent loss.

c. Remove standard Receiver End Plate from Buffer Tube.

NOTE: Before assembly, steps d-i, lightly lubricate threads of Lower Receiver and

Buffer Tube in accordance with Technical Manual 9-1105-319-23&P, pg. 0025-6

through 0025-8, November 2008 using molybdenum disulfide grease.

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d. Install CQD Rear Sling Mount Receiver End Plate onto Buffer Tube and screw

Buffer Tube clockwise until Buffer Tube just passes over the Buffer Detent

cutout.

e. Back off Buffer Tube counter-clockwise one turn and install Buffer Detent &

Spring.

f. Rotate Buffer Tube clockwise one turn until Buffer Detent and Spring are

captured by Buffer Tube.

g. Push Rear Sling Mount Receiver End Plate forward and flush to Receiver

compressing Takedown Spring and Detent.

h. Tighten Receiver End Plate Nut to 38 to 42 ft-lb, stake Receiver End Plate in two

places aligning with Receiver End Plate Nut.

Buffer Tube Installation Video

Take Down Pin Installation Video

2. Improved Buttstock

a. Pull down on lock release lever and remove standard Stock rearward from Buffer

Tube.

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b. Pull down on lock release lever and install Improved Cheek Weld Stock onto

Buffer Tube.

3. Ambidextrous Safety Selector

a. Remove machine screw and lock washer from Pistol Grip using 6” Screw Driver,

secure Selector Detent and spring for later use.

b. Remove standard Selector Lever.

Note: The Hammer must be in the locked (down) position to facilitate removal of Safety

Lever.

Note: The following steps c-f are in accordance with TM 9-1005-319-23&P, pg. 0021-20.

c. If not already in locked (down) position, depress Hammer until caught by the

Disconnector, install Ambidextrous Selector Lever into Lower Receiver.

d. Position Selector Detent with pointed end towards Selector Lever.

e. Place Selector Spring into spring recess in Pistol Grip and ensure Lock Washer

is installed onto Grip Screw.

f. Reattach Pistol Grip and tighten threaded screw to secure.

g. Place Right Selector Switch into appropriate groove cutout, install machine screw

and tighten using supplied T15 Torx key until finger tight, then another 1/8th a

turn.

Ambidextrous Selector Installation Video

End of Step B

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C. Upper Receiver Assembly

NOTE: Weapon must be field stripped and rendered safe and unloaded in accordance

with Training Manual 9-1005-319-10, June 2010 prior to proceeding with Block II

Carbine transition.

1. SOCOM Profile Barrel

Note: The following procedure is in accordance with TM 9-1005-319-23&P, pg. 0015-2

and pg. 0015-6.

a. Remove standard Handguard top and bottom by depressing Handguard Ring

and pulling away from weapon.

b. Lay on Upper Receiver on a flat non-marring surface and drive out Gas Tube

Roll Pin using 5/64 punch and brass hammer.

c. Remove Gas tube by sliding rearward until disengaged from front sight, slightly

twist until able to lift away.

d. Place Upper Receiver assembly into vise held in place using a Receiver Action

Block to prevent marring.

e. Align notches of Barrel Wrench to Barrel Nut and unscrew using a breaker

bar/torque wrench for leverage.

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f. Once Barrel Nut is loosed from Upper Receiver, slide Barrel Assembly forward

and clear of Upper Receiver.

NOTE: It may be necessary to remove certain components from SOCOM Heavy Barrel

assembly before installing barrel to Upper Receiver Assembly. If equipped, first remove

flash hider using Armorer’s Wrench, discard crush washer. Using 1/8” brass punch and

12oz. hammer drive out front sight rolls pins from left to right, then slide front sight and

handguard cap forward and off of barrel assembly.

g. Install SOCOM Heavy Barrel on to Upper Receiver and position index pin into

barrel alignment cutout.

h. Slide Bolt-Up Plate, anti-rotation tabs rearward, against Upper Receiver and then

Barrel Nut, notches facing forward.

i. Hand tighten Barrel Nut and then using supplied Barrel Nut Wrench attached to

torque wrench and tighten to 50 ft-lb.

j. Check headspace in accordance with TM 9-1005-319-23&P, pg. 0015-25

through 0015-26 if headspace is out of specification replace barrel assembly.

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NOTE: Bolt-Up Plate will be loose fitting and retain some movement, as per Daniel

Defense (DD) RIS-II Technical Manual Revision 2, September 2011.

SOCOM Barrel installation Video

2. Gas Block / Tube

a. Assemble Gas Tube into Gas Block and align roll pin hole and drive supplied roll

pin flush using a punch.

b. Slide Gas Block / Tube onto barrel until up against barrel shoulder, hand tighten

screws (2) with supplied 3/32” hex key.

Note: Ensure Gas Block is parallel to Upper Receiver or malfunction can occur.

c. Turn screws (2) another 1/8th turn to secure.

Gas Block Installation Video

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3. Rail Interface System II

NOTE: Removal of the Upper Assembly from the Receiver Action Block/Vise will be

necessary to install RIS II assembly. Installation as per DD RIS-II Technical Manual

Revision 2, September 2011.

a. Slide RIS II over barrel and locate onto Bolt-Up Plate, install 3/4" bottom screws

(2) and hand tighten.

b. Install remaining 7/8” screws (4) and tighten center screws first, then bottom

screws, and finally top screws all hand tight.

c. Once hand tightened check for Up/Down/Right/Left alignment of RIS II with

Upper Receiver and tighten to 29 to 32 in-lb. using supplied 5/32” hex key.

d. Attach lower RIS II section into Upper RIS II cutouts, secure using supplied

attachment screws and lock washers (4).

e. Remaining/Spare screws and lock washers (2) can be secured in the threaded

recesses forward of the M203 hanger tabs.

RIS II Upper Installation Video

RIS II Lower Installation Video

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4. Flash Hiders

a. Install M4-QD Flash Hider using supplied shim kit so that the middle slot of the

flash hider is located at 12 o’clock position (+/-5 degrees) when torqued to 20 to

30 ft-lb.

Note: Determining correct shim thickness is in accordance with Knight’s Armament’s

Company (KAC) Quick-Attach/Detach NT-4 manual, pg. 2 through 5, February 1997.

Flash Hider Installation Video

End of Step C

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D. Accoutrements

1. Folding Front & Rear Back-Up Iron Sights

a. Remove supplied Rear Sight by loosening machine screw on right hand side, or

if Detachable Handle unscrew thumb nuts and detach.

b. Install Front Folding Sight by placing the sight’s threaded screw into the forward

most recoil groove noted by the markings “FRONT SIGHT HERE” on the RIS II

and tighten threaded lock screw.

c. Install Rear Flip Sight by placing the sight’s threaded screw into the rearward

most recoil groove on the Upper Receiver, tighten threaded lock screw (all

models).

Folding Front & Rear Sight Installation Video

2. Day Optic

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Note: The following procedure is in accordance with Elcan Optical Technologies

SpecterDR Operator’s Manual, Revision C, pg.13 through 15, January 2010.

.

a. Install Day Optic by rotating throw levers located on the left hand side to approx.

90 degrees of the optic.

b. Place the optic’s recoil lug into the Upper Receiver recoil groove allowing for

clearance of the Rear Flip Sight and adequate eye relief.

c. Apply forward pressure on optic and rotate throw levers into their locked position.

3. Forward Sling Mount

a. Install Forward Sling Mount by removing the threaded screws (s) using a 7/64”

hex key.

b. Slide the sling mount from the front of the RIS II to the desired location, reinstall

threaded screws into middle of recoil groove to prevent damage to RIS II and

tighten.

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4. Gun Lights / Pressure Switches / IR Illuminator (Not Shown)

Note: The following procedures are to be completed in accordance with Insight

Technology Operator Manuals, M3X Gun Light, pg. 6, July 2003 and AN/PEQ-15

Infrared Illuminator, pg. 27-3, August 2006.

a. Install Gun Light by depressing lock bar lever and sliding into desired position,

release lock bar to secure into recoil groove.

b. Install Pressure Switch by depressing thumb latch and place the switch’s recoil

lug into the RIS II recoil groove in the desired location, release thumb latch to

secure.

c. Install the Infrared Illuminator by loosening the threaded mounting screw and

position the recoil lug in the desired recoil groove of the RIS II and tighten to

secure.

End of Step D

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PARTS LIST

A. Approved Components

Description Step NSN (If available)

Colt Defense 6920 M4 Carbine A through D N / A

CQD Rear Sling Mount B-1 (note 1) N / A

LMT SOPMOD Stock FDE B-2 (note 2) 1005-01-575-0756

Knight’s Ambidextrous Safety Selector B-3 (note 3) N / A

Colt Defense 14.5” SOCOM Barrel C-1 (note 4) 1005-01-471-5456

Daniel Defense Mk12 Gas Block C-2 (note 5) N / A

Daniel Defense RIS II FDE C-3 1005-01-547-2624

KAC M4-QD Flash Hider C-4 (note 6) 1005-01-460-3249

Knight’s Folding Front Sight FDE D-1 (note 8) 1005-01-473-1410

Knight's Folding Rear Sight D-1 1005-01-499-6868

Elcan SpecterDR FDE D-2 (note 7) 1240-01-533-0939

CQD Forward Sling Mount D-3 N / A

Insight M3X Gun Light FDE D-4 (note 9) 5855-01-538-9356

KAC QDSS-NT4 Sound Suppressor Not Shown 1005-01-437-0324

Insight AN/PEQ-15 IR Illuminator Not Shown (note 10) 5855-01-577-7174

Note: The AN/PEQ-15 is a highly regulated item due to FDA laser safety concerns are

unavailable for civilian purchase.

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Notes / Supplemental Information:

(1) This along with the Forward Sling Mount are not featured on every Carbine, it is

operator preference

(2) Many stocks are found in use with this platform including the Magpul CTR (1005-01-

591-6068), Colt Enhanced (1005-01-459-0734), and VLTOR Imod (1010-01-536-4742)

among others.

(3) The U.S. Military regularly uses the Knight’s Armament Company (KAC) Full-

Automatic version, as well as the Standard Selector.

(4) Colt M4 profile barrels (NSN 1005-01-233-8529) are often found on weapons that

have not gone through depot level overhaul, either profile would suffice.

(5) Knight’s Armament and Badger Ordnance also make Mk12 Gas Blocks for the

military, either of the three are acceptable.

(6) The M4-QD is the most prevalent and used in conjunction with the Knight’s

Armament QDSS-NT4 Sound Suppressor (NSN 1005-01-437-0324), however, a

Surefire 3P-Mk46 (NSN 1005-01-618-3966) in conjunction with a RC Suppressor (NSN

1005-01-599-6997) is now also in service.

(7) For iron sights, the Block II most commonly uses either the KAC 300 (NSN 1005-01-

449-6306) or 600-meter flip-up rear sight, or a standard issue MA-Tech 600-meter rear

sight (NSN 1005-01-484-8000). Though sometimes not equipped, a KAC flip-up front

sight in flat dark earth is the only issued front sight.

(8) The most common issued day optic is either the Elcan SpecterDR, sometimes

included with a Docter Red Dot, a Trijicon TA01-M4A1 (NSN 1240-01-412-6608, or an

EOTech model 553 (NSN 12440-01-533-09410, normally in flat dark earth.

(9) The US Military has used a number of flashlights to include the Dual Pressure

Switch compatible Insight WMX-200 (N/A), Surefire Scout (6240-01-532-4180), among

older legacy Millennium series.

(10) Infrared illuminators can be found in either flat dark earth or black and can include

the AN/PEQ-15A (NSN 5855-01-535-6166, AN/PAQ-4B (5855-01-361-1362), AN/PEQ

2A (NSN 5855-01-447-8992), and a host of others.

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Works Cited

M16/M4 Technical Manual 9-1105-319-23&P. Washington DC: Department of

Defense, November 2008.

M16/M4 Training Manual 9-1005-319-10. Washington DC: Department of

Defense, June 2010.

M3X Tactical Illuminator Operator’s Manual. Orlando, FL: Insight Technology,

July 2003.

AN/PEQ-15 Infrared Illuminator Operator’s Manual. Orlando, FL: Insight

Technology, August 2006.

QD-NT4 Sound Suppressor Operator’s Manual. Titusville, FL: Knight’s

Armament’s Company, February 1997.

SpecterDR (Dual Reticle) Operator’s Manual. Ontario, Canada: Elcan Optical

Technologies, January 2010.

Rail interface System (RIS) II Technical Manual. Black Creek, GA: Daniel

Defense Inc., September 2011.