FRONT SIGHT • November/December 200946

Most every multigun com-petitor's rifle has somekind of compensator ormuzzle brake adorning

the end of the barrel; but how well dothey work? Some of you may remem-ber the article "A Question of Com-pensation" from the Nov./Dec. 2007 is-

sue of Front Sight. This article contin-ues where that one left off, only addinga space-age twist. (The original articleappears at www.multigun.com/arti-cles.)

For that first article, seven differentcompensators were tested for recoil re-

duction and down force using test fix-tures that I created to collect objectivedata. I stress objective because if youperuse the internet halls of AR wisdomyou will find dogmatic allegiance tobrand "X" or "Y" based solely on feeland opinion. My effort then and nowis to bring you clear and repeatabledata and let you do the feeling andopining after you have made what Ihope is a more informed decision. As Istated near the close of the first article"one size does not fit all" and thatmaxim has not changed. There is noONE best brake. Too many variablesexist between competitors and theirchoice of equipment. The top 20 3-

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A 2nd Look AtCompensatorPerformance

Kelley’s recoil “sled.” The trigger ispulled by way of an inflating bal-loon. The transparent air line leadsto a pump. The laser pointer usedfor the remaining tests is shown at-tached to the handguard.

A 2nd Look AtCompensatorPerformanceBY PATRICK KELLEY, TY-14401

47November/December 2009 • FRONT SIGHT

Gunners use five or six different compensators to win on any given day. Honestly, you could just pick one, practice, andnever look back. However, competitors always seem to be looking for an edge. My endeavor here is to help you look.

My first article relied heav-ily on a test fixture called "TheSled." I took a Caldwell riflerest with a set of wheels at-tached, and set it up to rollrearward under the effects ofrecoil. The trick here was tobalance the affair to offerenough scale of movement tomake effective comparisonsbetween the un-braked(naked) rifle barrel and that

continued on page 67.

with each compensator attached. TheSled proved it could repeat this accu-rately over many tests. I expressedthose differences as a percentage ofrearward movement, e.g. if the un-braked carbine moved the sled 10inches, and with brake "X" the sledmoved 5 inches, that's a 50 percent re-duction.

While the Sled worked mar-velously for measuring gross recoil re-duction, I was not wholly pleased withthe test fixture for downward and lat-eral movement used in the first article.While it did show subtle differencesbetween brakes, it did not tell thewhole story.

Sometimes working too many 12-hour night shifts (at my real job as apower plant operator) can lead to in-teresting ideas! One of my transitionsfrom night to day shift had me awakewhen sleep was truly needed, musingon the downward-and-lateral data col-lection problem. I'd also been tinker-ing with capturing muzzle flash im-ages, so it wasn't long before my in-somniatic mind put the two together. Ireasoned that by employing a dark-ened range, still photography, a laserequipped carbine and a target, onecould show exactly where the muzzlemoves during recoil! Great idea,brain, now shut off and go to sleep!

To bring that sleep-deprivedidea to life I affixed a handheldlaser to the hand guard of thetest rifle -a 16-inch leftoverparts-built Frankenstein gun fir-ing IMI 55-grain FMJ-BT am-munition at 3050 fps. Then fir-ing offhand I would trigger ashot immediately after givingthe command to open the cam-era's shutter. A tripod mountedcamera and I stood 12 feet fromthe one-inch black aimingsquare pictured in the graphs.

The meaning of what yousee in the graphs may not bereadily apparent. At least it was

not immediately clear tome. Keep in mind that thelaser is moving within mywobble zone before and af-ter the camera shutter isopened. After calling (tomy lovely wife) for theshutter's release, I took theshot as soon as possible.You might think that Icould just leave the shutteropen for a long period. Icould, and I did, but theresults were unusable.

We as competitors are"programmed to hold cen-ter and follow through tocenter." With the shutteropen the laser "draws" my pre-shotwobble zone, the muzzle's movementthrough pulling the stock military trig-ger, and finally, driven by the effects ofrecoil, traces the graph you see here in-cluding my follow-through. Too longa shutter duration had my follow-through drawing back over the recoilimpulse trace, rendering it useless. Isettled on one half-second as a goodcompromise, minimizing my trace-over due to follow-through.

Three test sessions (with slightvariations in protocol) were com-pleted with multiple graphs createdfor each brake. This re-sulted in a lot of photos!

After many hours comparing images,here is how I interpret the informa-tion. In each photo, you will noticewell-defined sections, and sectionsthat are less dense. This less dense areais due to the "screen door" effect thatresults from the laser passing thoughthe pre bullet impact powder gas. Un-derstand that the fastest thing out ofthe muzzle is the expanding powdergas that drives and passes the bulletout of the muzzle. The "screen door"patterns shown in the selected photosrepresent the best and most concise re-coil trace pattern for each of thebrakes. Study the photos and you will

67November/December 2009 • FRONT SIGHT

WHAT ARE YOU

COMPENSATING FOR? continued from page 2.

Compensators Tested:Street Price Recoil Reduction

Arredondo 120 RR=60%Nordic Corvette 47 RR= 55%Nordic Tactical 35 RR=50%McArthur PGRS-1 175 RR=65%Carlson Flash 55 RR=20%Levang Linear 32 RR=0%SJC Lund 90 RR=75%TTi Eliminator 90 RR=75%DPMS Miculek 35 RR=65%JP Cooley 94 RR=62%Dreadnaught F2 85 RR=57%Triangle Rolling Thunder 82 RR=57%PWS DNTC 65 RR= 50%Middlebrooks Jet 85 RR=65%

A closer view of Kelley’s firing balloon system.

FRONT SIGHT • November/December 200968

see a short defined starting point (pre-shot), the compen-sator's initial influence on muzzle movement (screen door)and a second longer defined (post-shot) follow-through.

Each image is a complete "bang, extract, eject, feed andclose cycle." What I have not shown you is the trace createdwhen bolt locks back on the last shot fired. I do not have thetime at this point to cover it, but carrier weight makes a dif-ference! Not necessarily good or bad, just a difference. It didhowever give me an additional tool to better interpret thegraphs once contrasted with the others, as it illustrated wheneach compensator had "finished" compensating.

Having tested, designed, built, tuned and retested manyvarieties of rifle compensators over the last couple of years, Iam confident in being able to predict what attributes are ef-fective in reducing recoil. But I learned the rest of the storyafter digesting what was revealed in the graphs.

The greater the recoil reduction the less the muzzlemoves, right? Not necessarily. Several of the comps rankednear the bottom in the recoil reduction tests proved very con-trollable in the graphic tests. Recoil reduction may be THEfactor for a .338 Lapua bolt gun, but not for our AR bullethoses. Our performance criterion places a greater emphasisin making fast and accurate follow-up shots. To this, thegraphs tell much but not the entire story.

It is a safe bet that each brake that holds its tracing withinthe one-inch square would serve you well, but unless youshare my physical attributes, shooting technique and equip-ment the same result is not a given. A tall and lean competi-tor may want a compensator that does drive the muzzle be-low the aiming square. Reduced mass tends to offer less re-sistance to recoil, and muzzle lift would be more pro-nounced. A compensator tracing that moves to the right (anormal physical reaction for a right shoulder shooter) maythe cat's meow for the southpaw. Spend some time lookingover the data, I bet you will find a combination based on theinformation that will fit you!

Provided the performance is there what other aspects areimportant to you? Short, long, heavy, light, loud? Brand,cool factor or price? As stated previously too many variablesexist for me to pronounce one brake the best, so I will not. Iwill say there are some excellent values if you take cost intoaccount. There are other factors that affect controllabilitybut we'll leave those for the subject of another article. Fornow, I would suggest that you pick a couple of brakes andconduct your own subjective field-testing. In the end, it is notwhose compensator you are using, it is using the right com-pensator for you.

"If you think it makes adifference, it does."

Tips for tuning your AR compensator.BY PATRICK KELLEY, TY-14401

Ibelieve Jim Clark Senior (the patriarch of Clark Cus-tom) was the first to apply that title quote to firearms.Following that logic, I will outline a few methods tochange the way your muzzle brake behaves.

It is about moving gas, or more specifically directinggas movement. If you want to your comp to influence themuzzle to the left you must release a greater percentage ofgas on the right. Keep in mind you are working with a fi-nite amount of gas. Any change in flow favoring one di-rection reduces the gas flow and its ability to producework in all other directions.

How do you adjust gas flow? Break out a drill,Dremel®, mill or file and remove material! Make a portbigger; drill a "jet port" through a baffle or two. Tim Ublof Nordic Components offers this "by incrementallydrilling out the hole in the last baffle you can adjust theamount of down-force our Tactical Comp produces".Master gunsmith and all around good guy Benny Hill vol-unteers this advice on the tuning of his Rolling Thundercomp. "I've built this new comp to be tuned….While at therange, drill the jet ports at 12 and 3 o'clock a little at a timeuntil the muzzle quits moving". The JP Enterprises "BennyCooley" comp can be found with a jet port located at 9 or3 o'clock depending on which shoulder the shooter uses.The DPMS Miculek brake has created a legion of tuners.Due to its reasonable price and early entry into the mar-ket, this brake is often found in some modified form.Heck, I use the 223 version, reamed, re-threaded, andtuned to fit my Spring-field Armory M1A!

You can make effectivechanges without remov-ing material through"Clocking". This is sim-ply indexing where thecomp is positioned at fi-nal assembly. Many aright shoulder shooter will report an "up and to the right"movement in recoil. To combat that, "clock" the comp(very near the 1:30 position) to vent its upward gas flowin the same direction.

Whatever the comp or method,

Clock and try,Drill, cut or buy;Only you know what you are compensating for!

The ubiquitousMiculek comp.