Franklin Armory 5.56 NATO Bolt Carrier Group BCG Black 00-52018-BLK. 56 NATO. 6.8 SPC. 6.5 Grendel. 7.62x39. 450 BM. Carrier machined from 8620 Steel. M16 Weight. Properly staked gas key. Polished finish. Franklin Armory logo included. Treated with...