The 6.8 mm Remington SPC is a rifle cartridge that was developed with collaboration from individual members of United States Special Operations Command. The 6.8 mm SPC (6.8×43mm) is based upon the .30 Remington cartridge, it’s size is midway between the 5.56×45mm NATO and 7.62×51mm NATO in bore diameter and velocity. It uses a .277 diameter bullet (6.8mm), which is the same diameter bullet as the venerable hunting cartridge .270 Winchester uses. It is particularly adaptable to current 5.56 mm NATO firearms, the cartridge overall length being comparable.
The 6.8 mm SPC has become a popular choice for those familiar with the AR-15 style rifles. If you have an AR-15 lower receiver, you can buy a 6.8 upper and some 6.8 mags and you then have an excellent hunting platform in an AR-15 that utilizes the 6.8 cartridge as easily as changing the upper and mags.