small arms review article on barrett (nov 2006)

35The Small Arms Review • Vol. 10, No. 2 • November, 2006

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The Barrett Model 6486.8mm Rem SPC

by Christopher R. BartocciEver since the change over from the 7.62x51mm to the current 5.56x45mm there has

been controversy between two fundamental schools of thought on what a military car-tridge should be. The United States military can be summed up in one word: tradition.

In the 1960s, that tradition clouded the vision that a new dawn of small armsdevelopment in both concept, mechanics and ammunition had come. Still en-trenched in the “one shot, one kill” mentality, our soldiers were sent into com-bat in Vietnam with the M14 which many considered to be an inferior weaponto the AK47 assault rifle that the enemy used. The enemy were able to laycontrolled large volume of automatic fire on positions which, in a meetingengagement, will win you a fight. Our soldiers were equipped with a heavy

recoil rifle that was impossible to control on fully-automatic. The accuracy was of nouse because the enemy could not be seen.

With much trepidation, the military adopted the AR-15 rifle destined to become theM16/M16A1. A new age of small caliber high velocity cartridges gave way to provid-ing an individual soldier with firepower he had never had before. The 5.56x45mm

cartridge utilizing a .224 diameter 55-grain full metal jacketed bullet proved

Left: The Barrett M648 upper receiver conversion and magazineon a Colt M4A1 lower receiver. Notice the Aimpoint M68 reflexsight and the retracted buttstock. Also notice the A.R.M.S., Inc.vertical pistol grip.

Below: The M855 Ball projectile (top) and a cut-away (bottom). No-tice that there are three components to this bullet. The copper jacket,the steel penetrator core and the lead plug. This bullet design has causedthe major accuracy and terminal performance problems that have beenexperienced with the M16A2 and M4 carbines. (Photo by Jim Wesley)

36 The Small Arms Review • Vol. 10, No. 2 • November, 2006


to be a great asset to the American fight-ing man with the ability to have a light-weight rifle that was completely control-lable on fully-automatic fire and the sol-dier could carry more than twice the com-bat load with an M16 than he could withthe heavy M14 rifle.

The Third GenerationM16A2 and M855 Ball

With the product improvements of theM16A2 the weapon system was enhanced.Due to the heavier 62-grain bullet, 1 turnin 7 inch rifling twist and new fully adjust-able rear sight, both penetration and longrange accuracy were enhanced. However,the culprit of the future problems withammunition terminal performance wouldcome from the ammunition, the M855 Ball.

The M855 Ball is a three piece bulletconsisting of a copper jacket, lead plug anda steel penetrator core in the tip. This bul-let was designed for a machine gun, not arifle. With the onset of the Global War onTerrorism, terminal deficiencies werefound using M855 Ball, particularly in M4carbines, when striking thin, malnourished,Taliban and Iraqi soldiers. There was a

serious inconsistencyin at what point thebullet would yaw andsplinter. Some lots ofammunition wouldpenetrate onlyslightly within inchesand yaw and splinter.Others would gostraight through andnever yaw nor splin-ter. This caused se-rous knockdownproblems particularlywith the decreasedvelocity of 14.5 inchcarbine barrel.

A solution put forthby the United StatesSpecial Operations Command (SOCOM)was the creation of a new and improved5.56x45mm cartridge that would increaselong range accuracy and terminal perfor-mance with consistency. Accuracy is seri-ously degraded in the M16A2/A4/M4 dueto the inherent characteristics of the M855bullet. The penetrator core degrades ac-curacy and if not manufactured properly,the center of gravity will be off causing

the bullet to become a “flyer.” Addition-ally, in the area of terminal performance,there was no consistency from lot to lot onwhat exactly it would do upon hitting a hu-man target.

The answer was the Mk 262 MOD 1 car-tridge that SOCOM adopted. This is a Si-erra 77-grain open tip match bullet loadedby Black Hills. This is undoubtedly themost effective 5.56x45mm military car-tridge in the world manufactured to matchgrade specifications with combat reliabil-ity. The long range accuracy was drasti-cally increased and its terminal perfor-mance enhanced. This new projectileworks well regardless of the type of targetand performs considerably better on hu-man targets in all known distances andconditions. This round is used almost ex-clusively by SOCOM operators in theirM4A1 carbines and Mk12 rifles. This so-lution satisfied most of the SOCOM op-

Right: Three bullets. The first (left) is the M855 ball projec-tile with the penetrator core shown above. The middle pro-jectile is the 77-grain Open Tip Match bullet that is loaded inthe Mk262 MOD1 ammunition and the last is the 115-grainSierra Open Tip Match bullet as loaded in the pre-produc-tion 6.8mm Rem SPC cartridge.

Left: Performance chart compar-ing the terminal performance ofthe 5.56 M855 Ball, 5.56x45mmMk262, MOD 0 and two 6.8mmSPC cartridges. Notice the simi-larity of the Mk262, MOD 0 andthe 110-grain 6.8mm SPC car-tridge. The penetration and tem-porary/permanent wound cavitiesare very comparable. The othertwo show significantly more pen-etration. Courtesy USSOCOM



erators: except for one.

The 6.8x43mm REM SPC

The 5th Special Forces, particularly MSGSteve Holland, felt that there was still roomfor improvement. The concept was notoriginal. The U.S. military experimentedwith the possibility of the 6mm caliber pro-jectile being the ideal compromise of accu-racy, range and terminal performance. Inthe late 1970s the concept was abandonedin favor of the 5.56x45mm battle rifle.

With the assistance of the U.S. ArmyMarksmanship Unit, Holland came up witha concept for a 6mm cartridge that could befired in the M4 platform. The starting pointwas the .30 Remington cartridge which ismerely a rimless .30-30 Win. round. It wastrimmed and resized to accept a 6.8mm pro-jectile. This concept, along with the hand-loaded experimental ammunition and CADdrawings went to Remington Arms. Rem-ington wanted to aid in the Global War onTerrorism so they took on the task of devel-oping the ammunition.

The 6.8mm REM SPC cartridge has beenmostly a myth for the last few years due tothe fact it has been developed quietly andkept proprietary. No ammunition has beenmade as of this writing in large quantitiesdue to the fact the ammunition is being per-fected before it will be shipped. Reming-

ton has reported three small runs of ammu-nition including ball and match grade am-munition. Hornady has also produced someloads in this new caliber.

The Firearms

Prototype rifles were manufactured byPrecision Reflex, Inc. (PRI). Dave Dunlapassembled upper receivers with free float-ing handguards or A.R.M.S., Inc. SIR sys-tems and the OPSINC silencer and muzzlebreak. Dunlap also was charged with de-signing the magazine which is different fromthe standard 5.56x45mm magazine. Cur-rently, PRI has been the only producer of6.8x43mm Rem SPC magazines. PRI alsoproduces complete upper receivers cham-bered in the 6.8x43mm Rem SPC cartridge.

The Barrett M648

At the 2004 SHOT Show, Ronnie Barrettunveiled a new product line: his M648.This company, dedicated to.50 BMG caliber special-ized weapons, introducedthe first production6.8x43mm Rem SPC fire-arm and has taken the leadon this project. While thecartridge is still technicallyunder development (to be

more correct would be to say “tweaked”),Barrett has teamed up with Peter Forras towork with Remington to optimize theweapon and cartridge. Forras has spentmuch time down at Remington workingwith them to perfect the 6.8x43mm car-tridge.

The rifle has been based on the standardM16-platform. Barrett offers the rifle inboth commercial and law enforcement/military configurations. The “bells andwhistles” are the same for both versions,the only real difference is the use of selec-tive fire, flash suppressors, bayonet lugsand telescopic stock on the law enforce-ment/military models.

The weapon as offered uses a mid-lengthgas system developed by Mark Westromof ArmaLite, Inc. This mid length gas sys-tem changes the location of the gas portby placing it further forward than the car-bine and slightly behind the rifle. Thisgives two major advantages: reliability anddurability. By putting more distance be-

Close-up showing the threads and thread protector for mountinga silencer. The front sight is engaged on this Barrett designed frontsight assembly. This particular carbine is equipped with a muzzlebreak. This greatly increases controllability on full automatic.

Right: To the left is a 100-grain Barnes X bullet that was fired at50 yards into a 1/4 inch steel plate. The same bullet (right) firedinto ballistic gelatin.

38 The Small Arms Review • Vol. 10, No. 2 • November, 2006


tween the bolt carrier and gas port, lowerport pressures are created resulting in thebolt assembly’s velocity being slower. Thisincreases reliability in extraction as wellas extending the life of the bolt and someof the trigger components.

The barrel is manufactured by FredFedderson. This 1 turn in 10 inch twistbarrel is chrome plated and is currentlyavailable in 16 inch length only. Barretthas plans on offering 12 and 20 inch bar-rels in the near future. The commercialversion has a muzzle check similar to theone used by ArmaLite, Inc. The law en-forcement/military versions use the stan-dard M16-style muzzle break/compensa-tor

The M648 gas block utilizes a foldingfront sight assembly. This assembly wasdesigned by Barrett. On the law enforce-ment/military version, there is a threadedcollet on the edge of the gas bock to in-stall the silencer.

The Mid-Length SIR System

The A.R.M.S. Inc. SIR (Selective Inte-grated Rail) system developed by RichardSwan is the solution for many problems

associated with military use of this type ofweapon system. The SIR system is a free-floating handguard assembly that attachesto the carrying handle by a sleeve that goeson top of the rail (thus protecting it) as wellas directly to the barrel nut. This give anextended top rail that runs the entire lengthof the upper receiver to the front sight as-sembly. There are four Mil-Std 1913 railsthat enable optics, laser, flashlights andwhatever other accessories that may beneeded for the rifle with no effect on thebarrel and its performance.

Free floating a military weapon hasmany benefits. First would be accuracy.With nothing impeding on the harmonicsof the barrel, better uniform accuracy isachieved. Additionally, the barrel remainscooler as there is significantly better aircirculation enabling the weapon to firelonger on full automatic fire. Another ben-efit, particularly with a hot barrel, pullingdown on a vertical fore grip will not causethe barrel to bend or droop. The SIR sys-tem may also have a M203 grenadelauncher attached to it. All the currentmodels of the M648 feature the A.R.M.S.Inc. SIR system as well as the ARMS #40L emergency flip-up backup sight.

The Bolt

The bolt carrier is standard M16/AR-15. The difference lies in the bolt itself.The bolt was designed by Chris Barrettand is manufactured by Lewis Machine& Tool (LMT). The bolt uses the trade-mark dual extractor spring “lobster tail”extractor manufactured by LMT as it ismore durable and reliable. The bolt hasother similarities to the LMT Enhancedbolt but Barrett made some changes inmaterials and specifications specificallyfor the M648. The bolt has a nickel plat-ing on it.

Configurations

The M648 comes as a full weapon withfixed rifle stock as well as selective firecarbine lower receiver with the telescopicbuttstock. The system is also sold as anupgrade or a conversion kit which will in-clude the entire upper receiver assemblyand magazine. The conversions can beobtained with either selective fire bolt car-riers or semiautomatic only. It should benoted that when putting a conversion ona standard selective fire carbine lower re-ceiver, the “H” buffer should be used.This is the buffer with two steel weightsand one tungsten. If the standard threesteel weight buffer is used the carbine mayexperience bolt carrier bounce resultingin light strikes on full automatic. This isnot an issue with the full length rifle se-

Below: Close-up view of the A.R.M.S. SIR system that was specifically designed for the Barrett M648. Notice it saysCAL 6.8 just above the end of the ejection port. This is the special design for the mid-length gas system. The bottom ofthe hand guard may be removed to install a grenade launcher.

Left: The bolt utilized on the M648designed by Chris Barrett. It is amodified version of the LMT En-hanced bolt but customized for the6.8 SPC cartridge. Notice the “lob-ster tail” extractor with dual extrac-tor springs.



lective fire lower receiver. Semiautomaticguns can use either due to the bolt groupwill have sufficient time to lock beforethe next shot is fired. There has beensome discussion about Barrett eventuallycoming out with a piston driven mecha-nism for this weapon system.

Shooting Impressions

The rifle received for testing was a lawenforcement/military upper receiver witha standard semiautomatic only lower re-ceiver. The author’s own Colt M4 fullautomatic carbine lower was used for fullautomatic testing. The semi-automaticonly lower receiver was equipped with anLMT two-stage match grade trigger. Theoptics used were the M68 Aim PointComp II, EOTech holographic sight aswell as the standard backup sights. Ap-proximately 700 rounds were fired in to-tal in both semiautomatic for accuracy aswell as fully automatic for functionality.The magazine used was a PRI made 28-round steel magazine. The ammunitionwas manufactured by Remington.

Fully-automatic tests were conductedin close quarter battle conditions. Tar-gets ranged from 5 to 25 meters. Thecyclic rate was about the same as the stan-dard M4 carbine and recoil was really notthat much more. There was no problemcontrolling the weapon. The EOTechsight made shooting easier allowing botheyes to remain open increasing speed andaccuracy. By adjusting the brightness ofthe sight, it was useful for both close tac-tical work as well as short range sniping.

Conclusions

The 6.8mm Rem SPC is without a doubtan improvement over the existing

5.56x45mm for military use. But thequestion is, how much better? The car-tridge unfortunately has a very steep up-hill battle ahead of it once the militarycommunity gets a hold of it. The weaponitself is not an issue. The M16-baseddesign is well proven. But in order forSOCOM in particular to adopt such a car-tridge for use will be a gigantic undertak-ing. First and foremost it has to be morethan better, it will have to be drasticallybetter and offer a large advantage. Sec-ond, and perhaps the most critical, willbe logistics. The cartridge will be at bestused by SOCOM operators and themalone. From a logistical standpoint, add-ing a new cartridge into inventory, in par-ticular one nobody else in the serviceuses, can cause serious problems. OnceSOCOM operators are deployed they be-come part of the unit they are assignedand along with that goes their supply.Having non-compatible ammunition canput the operators at risk given they do nothave re-supply specific to them.

The Barrett M648 and 6.8x43mm RemSPC ammunition performed flawlesslyand accurately. Barrett has not been tooquick to go into production due to the factthey have waited until the developmentof the rifle and ammunition was com-pleted insuring their customers get a fi-nal production weapon and not a semi-prototype. As of this writing, after morethan three years of advertising and manu-facturing of barrels to fire this new car-tridge, the ammunition has yet to be com-pleted and put into full production. Thisweapon and cartridge will undoubtedlyfind a following in law enforcement andcommercial shooters and competitors. Asfar as the military use of this weaponssystem, only time will tell.

small arms review article on barrett (nov 2006)

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