In military actions since Sept. 11, 2001, special operations troops have found the M4 carbine and the M855 62-grain round it fires sadly lacking in penetration and lethality. These shortcomings have inspired a new cartridge, the Remington 6.8 Special Purpose Cartridge (SPC) that boasts 30 percent more energy yet still fits within the AR-15/M-16/M-4 weapons envelope.
Barrett Manufacturing has just introduced its M468 carbine. Factory-equipped with a rail system and chambered for the hot new 6.8 SPC round, this rifle should create a lot of interest in the tactical community.
Made to Perform
Barrett’s M468 carbine chambered for the new 6.8 SPC is all business. From its forged receivers to its tough military parkerized finish to the rail handguards it wears, every feature of the M468 is well thought out and includes the proven attributes that experienced operators ask for.
Case in point is the weapon’s A.R.M.S. Selective Integrated Rail System that offers an unsurpassed ability for the user to attach any number of accessories. The system free floats the barrel and promotes drastically enhanced cooling. It also allows the user to put a rail where he wants it and not have a rail where he doesn’t. The system is solid and wiggle free and also completely noiseless.
The rear sight folds down flat when not in use and is held closed with a spring-loaded lock lever to prevent inadvertent opening. Pushing down on the sight and moving the lever allows it to open. There’s a small knob on the port side of the sight for windage adjustment. Elevation adjustments must be made on the front sight.
Barrett uses a front sight/gas block combo part. The front sight folds down flat against the gas block for use with optics and uses a spring-loaded ball detent to hold it in the “up” position when deployed. The forward portion of the gas block features threads for use with a suppressor and comes with a knurled thread protector cap. To preclude someone accidentally putting a 5.56mm flash hider on the gun, Barrett uses a different thread pitch. The two-port muzzle brake is needed to index the suppressor properly. The company uses a 16-inch chrome-lined barrel on the M468 and rifles them with a 1:10-inch twist to stabilize the bullets. Suitable bullets are currently difficult to find in stock, but I’ll get to that later.
Barrett’s new carbine is impressive by itself, but I’m also impressed with the new 6.8 SPC cartridge the M468 is designed to use.
In 2002, the Army Marksmanship Unit, members of Special Operations, and Remington Arms combined forces to develop the new 6.8 SPC cartridge. The design engineers started with a .30 Remington case. They shortened it and relocated the shoulder. Then they seated a 115-grain .277-inch bullet, the same diameter used in the popular .270 Winchester cartridge, to give the cartridge the same overall length as the 5.56 mm round. The projectile has a ballistic coefficient of .350, offering extended accuracy and lethality. Additionally, its trajectory is very close to that of a .308 Winchester out to 600 yards.
Of the 6.8 SPC loads that I tried, Silver State Armory’s 115-grain X-Treme load produced the highest velocity, registering 2,605 feet per second from the Barrett’s 16-inch barrel and 1,733 foot pounds of energy. Compare that to the military’s 5.56mm M855 62-grain bullet, which from a 16-inch barrel produces 2,911 feet per second in velocity and only 1,167 foot pounds of energy.
These figures represent a more than 30-percent increase in energy and that’s a significant enough increase for the U.S. military to take a good hard look at it. Other than the barrel, the change in caliber requires very little modification to an existing 5.56mm M-16/M-4/AR-15 weapon.
Because the casehead of the cartridge is larger in diameter than the 5.56mm, the bolt will have to be changed to accommodate the larger rim. Likewise, you must use magazines designed especially for the 6.8 SPC, as the larger diameter of the cases will cause 5.56mm magazines to swell and become useless. Nothing needs to be done to the lower of the weapon. The user can quickly change between the 5.56mm and 6.8 SCP calibers, simply by switching uppers.
Testing the Gun
Trigger pull on my test sample broke crisply at four pounds. Pulling out the rear takedown pin and cracking the rifle revealed that Barrett uses a two-stage, non-adjustable trigger. For this type of weapon that makes a lot of sense, as there are no worries about an engagement or overtravel screw backing out and rendering the weapon inoperable or worse.
My test sample is equipped with a standard A2 stock, though the receiver will accept any mil-spec stock system, collapsible or otherwise. Barrett also offers a law enforcement-only model that is select fire and comes equipped with an adjustable M4-style stock. As with the buttstock, Barrett uses a standard A2 pistol grip on the M468.
The biggest problem I faced in evaluating this weapon was finding ammunition. Because of the military interest in this caliber, civilian hobbyists have been watching the development very closely. Several manufacturers now offer complete rifles and dedicated 6.8 SPC uppers. Because of this, ammunition is in short supply.
I called Remington and asked for a small sampling and they said that they would put me on the waiting list but that it might be six months or more before they could get me any ammo. I also called Hornady and the results were pretty much the same. Finally, a friend found some Remington ammo at a retail gun store in Phoenix and bought 10 boxes for me at an inflated price. Half of the ammo was 115-grain full metal jacket and the other half had 115-grain open tip bullets. With ammo in hand, I got down to the work of shooting.
I did all of my shooting from a seated rest utilizing a rifle rest. I mounted a Trijicon 3 x 9 Accupoint scope on the rifle to make sure that I was able to wring every last bit of accuracy out of the gun. After firing a number of groups with the 115-grain FMJ I was a little worried. Most of the five-shot groups were right around two inches and I just knew that the Barrett was capable of better accuracy. I then switched to the 115-grain open tip bullets and groups opened up almost twice the size, with my best five-shot group measuring about three inches.
Now I was really worried. I just knew that this rifle had to be capable of shooting tiny groups. The problem was finding a different variety of ammunition to test it with.
Out of desperation I did an Internet search for 6.8 SPC ammunition. Among the hits that I got was an outfit called Silver State Armory, whose Website advertised ammo ready for immediate delivery. The company was kind enough to send me samplings of three different loads. You can see from the accuracy chart on page 65 that I had better luck with this ammunition. All three of these loads delivered acceptable tactical accuracy from a carbine.
Surprisingly, it wasn’t the load with the Match King bullet that delivered the best accuracy, but rather a hunting load with a 110-grain exposed lead tip bullet. I was able to group five shots from a hot barrel into a group that measured just .87 of an inch center-to-center. This is the kind of accuracy that I knew the Barrett gun was capable of.
Despite the gun delivering far more energy than a 5.56mm rifle, I was just barely able to notice that the recoil was heavier and it was far from punishing. It’s a very comfortable gun to shoot even when you’re shooting a lot of rounds.
I took some steel targets out into the desert to see how well the M468 handled during rapid fire and target transitions. I mounted an aluminum foregrip and a Meprolight MEPRO 21 reflex sight on the carbine. This new offering from Meprolight features an amber aiming dot just 4.2 MOA in diameter and has tritium backup for low-light and no-light shooting. I like the new quick release levers that make mounting the reflex sight a snap.
With the targets set up at about 50 yards, I had no problems double-tapping the steel. The MEPRO 21 reflex sight made transitions between targets extremely fast and the Barrett’s crisp trigger made it possible to deliver fast and accurate hits. During these exercises it was impossible for me to tell the difference in controllability between the 6.8 SPC and the 5.56mm cartridges.
Because of the ammunition shortage I only fired about 300 rounds through the Barrett M468. Although that’s on the low side for an evaluation, I found the carbine to be 100-percent reliable. During the testing there were no stoppages or failures. Barrett shipped two 25-round PRI magazines with the carbine and they worked just fine. The same company also offers five-, 10-, and 15-round mags. I wish that I’d had one of the shorter mags for the bench shooting, as the 25-rounder interfered with my rifle rest because of its length.
The value of the 6.8 SPC cartridge is demonstrable on paper and early field reports are favorable. Whether or not the military adopts the cartridge will heavily affect its popularity with officers and agencies. But more horsepower from the same size weapon without degradation of control has to be a good thing. Barrett’s M468 is an exceptional piece of equipment. It’s accurate and reliable and possesses everything a tactical operator will need. Barrett also offers 6.8 SPC uppers separately. Law enforcement purchasers need to specify if they want a full-auto bolt carrier assembly.
Mike Detty is an NRA-certified rifle, pistol, and shotgun instructor. A certified rangemaster and competition shooter, Detty served as an officer in the U.S. Marine Corps and holds a degree in criminal justice from the University of Arizona.
Barrett Firearms M468 - Features and Accessories
• Dual-spring extractor system
• Muzzle brake
• Folding front sight and gas block
• 30-round magazine
• Two-stage trigger
• Law enforcement and military configurations available
• ARMS Selective Integrated Rail (SIR) system fore end
• ARMS folding rear sight
M468 CarbineCaliber: 6.8 Remington SPC
Operation: Semi-automatic, gas operated
Overall Length: 35.4 inches
Barrel Length: 16 inches (chrome lined)
Weight: 7.3 pounds