At the request of the U.S. Military, PRI produced a wider floor-plate (right) which could easily be differentiated from 5.56 magazines (left) by feel.
Factory loads shoot 110 or 115-grain bullets at 2550 to 2650fps from 16 to 18-inch barrels. Ballistic trajectory is very similar to 75 or 77-grain .223, or 150-grain .308 loads from 18 to 20-inch barrels. Silver State Armory developed a load with a new 115-grain copper-plated lead flat-point bullet engineered specifically for 6.8 SPC by X-Treme bullet. Instead of a costly copper jacket, the lead projectile is plated with copper, producing a bullet that appears like a TMJ, but has terminal performance similar to the best OTMs. The SSA 115-grain X-Treme load shoots 2625fps from a 16-inch barrel, and their 115-grain Sierra MatchKing (SMK) load shoots 2640fps from the same barrel length. The Hornady 110-grain V-MAX shoots 2550fps from a 16-inch barrel. Remington 115-grain OTM ammunition chronographed at 2500fps from my 18-inch barrel in late 2005.
6.8 SPC takes full advantage of the modularity of the AR-15 design; a 6.8 SPC upper can be used on any standard complete lower.
Reloaders have an easy time with 6.8 SPC. Excellent bullet choices include the Hornady 115-grain OTM and 110-grain V-MAX, the Sierra 115-grain SMK and 110-grain Pro-Hunter JSP and the 110-grain Barnes TSX, but any 0.277-inch bullet may be used. Brass is available from Silver State Armory and Remington, both of which use large primer pockets. The Hornady brass, currently only available in loaded ammunition, uses small primer pockets, which should provide more case head strength. The developers of 6.8 SPC originally chose small primer pockets, however Remington suggested using large primers for absolute reliability in extreme cold. Later testing showed that small primers were virtually as reliable.