Rosco 5.56 NATO / .300 BLK Nitride Bolt Carrier Group

The Rosco® 5.56 NATO / .300 BLK Nitride Bolt Carrier Group (BCG) features an 8620 steel carrier with a corrosion-resistant Melonite finish with a 4130 steel gas key that's attached with Grade 8 hardware and properly staked. The cam pin is hardened 4340 steel construction while the firing pin is 8740 steel, center-less ground and hard chrome coated, and built to Mil-Spec. The bolt is 9310 steel, properly heat-treated, and MPI/HPT tested while the extractor is 4340 steel. Plus, the ejector is constructed with S7 tool steel. Full-auto rated.