This M5 .308 / 7.62 bolt carrier is a firing mechanism for your big-bore rifle build. It features a mil-spec phosphate finish, is made of steel, chrome lined gas key and firing pin channel, and a forward assist serrations. The bolt features double o-rings and springs, is made of steel and is has a multi-caliber bolt designed to function with .308, 7.62x51, 6.5 Creedmoor, .338 Federal and other .308 based cartridges. Included is a bolt carrier, complete bolt, firing pin, cam pin, retaining pin, and a Aero Precision "A" logo. This model has a black nitride finish.