Chuck:
The 6.8 mm Remington Special Purpose Cartridge (aka 6.8 SPC, 6.8 SPC II & 6.8×43mm) is a rimless bottlenecked intermediate rifle cartridge that was developed by Remington Arms in collaboration with members of the U.S. Army Marksmanship Unit, United States Special Operations Command[5] to possibly replace the 5.56 NATO cartridge in a Short Barreled Rifle(SBR)/Carbine.
Based upon the .30 Remington cartridge,[6] it is midway between the 5.56×45mm NATO and 7.62×51mm NATO in bore diameter and muzzle energy. It uses the same diameter bullet (not usually the same weight) as the venerable .270 Winchester hunting cartridge.
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