6.8 mm Remington Special Purpose Cartridge (aka 6.8 SPC, 6.8 SPC II & 6.8×43mm) is a rifle cartridge that was developed by Remington Arms in collaboration with members of the U.S. Army Marksmanship Unit, United States Special Operations Command to possibly replace the 5.56 NATO cartridge in a Short Barreled Rifle(SBR)/Carbine.