Cartridge Profile—6.8 Remington SPC – When U.S. Army Special Operations Command teamed with Remington to design the 6.8 Remington SPC (Special Purpose Cartridge), a.k.a. 6.8x43mm, there were specific goals. The first was to improve on the exterior ballistics of the 5.56mm NATO in a cartridge that would operate in an AR-style. This was in response to reoccurring reports from military troops that the 5.56mm NATO lacked the energy delivery to decisively incapacitate enemy combatants. The secondary goal was a round that performed well from the 16-inch barrel of the military’s standard-issue M4 carbine. The SPC maximized knock-down energy without sacrificing undue magazine capacity or conspicuously increasing felt recoil.
A 6.8mm (.277 caliber) bullet diameter was chosen to split the difference between the 6.5mm (.264) and 7mm (.284). Originally the SPC was loaded with 115-grain bullets sent at 2,800 fps and producing about 2,000 foot pounds of energy. There is an improved version—the SPC II—that will meet those specs, but the version SAAMI accepted in 2004 produced about 2,625 fps and 1,759 foot pounds of energy while shooting 115-grain bullets. This still gives the SPC a 44 percent increase in energy delivery over the 5.56mm NATO at 100 to 300 meters.
By the time SAAMI approved the 6.8 SPS the round was already being carried by special operation forces in foreign wars. By 2007 U.S. SOCOM and the Marine Corps summarily abandoned the cartridge, due largely to war efforts shifting from the close-quarters urban combat of Iraq to mountainous Afghanistan where longer target engagements begin to tax the SPC’s capabilities. The Department of Defense also broached logistical and cost concerns. Still, the Jordanian Army officially adopted the round in 2010, and the Saudi Royal Guard soon after.
As a sporting cartridge the 6.8 SPC remains most popular with nighttime hog hunters employing thermal-imaging optics. Its closest competitor, the 6.5 Grendel, was developed by Alexander Arms around the same time the SPC appeared. The SPC produces more velocity and hits harder at ranges inside 200 yards, and outperforms the 7.62x39mm Soviet cartridge, while superior ballistic coefficients give the 6.5 Grendel a cumulative advantage at distances exceeding 250 yards. The 6.8 SPC produces conspicuously less recoil than both.
Creating a 6.8 SPC rifle from an existing AR-15 involves a barrel, bolt and magazine swap, or simply pinning a complete upper into place and swapping mags. Rifling twists from 1:12 to 1:10 are encountered, with 1:11 proving most common and easily stabilizing short .277-inch bullets up to 120 grains best suited to the cartridge and its AR vehicle. The SPC performs especially well from short barrels, gaining only negligible velocity from barrels measuring more than 16-18 inches long.
Cartridge Profile—6.8 Remington SPC – I’ve not found the SPC particularly challenging to load. Reliability has remained 100 percent with overall loaded lengths (OALs) around 2.25 inches. The SPC is a relatively short and fat design, short barrels doing best with relatively fast to medium-fast powders. I’ve conducted fairly extensive load development for the cartridge and have established decided powder preferences.
The round does best firing bullets weighing from 85 to 120 grains, heavier bullets reaching a point of diminishing returns by unduly intruding into powder space due to AR-15 magazine limitations. Even bullets such as the 1.12-inch, 100-grain Hornady CX and 1.125-inch 120-grain Hornady SST can result in heavily compressed loads with most stick powders. Compressed loads normally don’t concern me, but in an AR severe compression can lead to creeping spring-back that causes jams and live rounds stuck tightly into the chamber. The first time a round jams tightly into the lands with only a small charging handle to grasp, you’ll understand by aversion.
SPC cases come with large or small rifle primer pockets. Hornady, Federal Fusion, American Eagle and Silver State Armory (SSA, by Nosler) cases hold small rifle primers, Remington cases holding large rifle primers. The 6.8 Remington SPC was formed from a .30 Remington parent case, but due to massive Middle Eastern ammunition contracts SPC cases are easily secured. Trim-to length is 1.676 inches.
Cartridge Profile—6.8 Remington SPC – I use my 6.8 SPC almost entirely for nighttime hog hunting with thermal optics, so look for drop-right-there terminal performance. One such load includes Hammer Bullets’ 85-grain Shock Hammer, a nontoxic monolithic copper hollow point, combined with Hodgdon’s CFE BLK powder. I also like Speer’s 90-grain Gold Dot, a lead core bullet with electroplated copper jacket that provides near 100 percent weight retention. It has also paired well with CFE BLK.
Hornady’s 100-grain CX, another nontoxic mono-copper design, is led by a red polymer tip and has proven quite compatible with Shooters World Tactical Rifle powder. Nosler’s 110-grain AccuBond includes a bonded core and tapered jacket, the poly tip encouraging beautiful mushrooming at velocities as low as 1,800 fps. Ramshot X-Terminator has proven best with this bullet. Speer’s 115-grain Gold Dot is a true thumper, while also providing a .401 G1 ballistic coefficient (BC) that makes it welcomed on longer shots. Accurate A-2230 has proven quite compatible with the heavier Gold Dot. At the heavy end Hornady’s 120-grain SST, with its Super Shock Tip- and InnerLock internal crimp, also provides an impressive .400 G1 BC for longer shots. My best load involves Ramshot TAC.
Whether hunting wild hogs or white-tailed deer, the 6.8 Remington SPC is a fine cartridge for big-game hunters who prefer the AR-15 platform.