Nickel Boron M16 Bolt Carrier Group 5.56/.223/300 - $89.95 Nickel Boron M16 Bolt Carrier Group 5.56/.223/300 BLK (BCG) The Nickel Boron M16 Bolt Carrier Group 5.56/.223/300 BLK (BCG) from Black Rifle Depot is a high-quality, precision-machined product with exceptional performance and easy