Tiger Rock AR-15 7.62x39 Bolt Carrier Group BCG Black Nitride 9310 Bolt. The ultra-hard and corrosion-resistant Black Nitride ensures this BCG's continued reliability and precision. Specifications for Tiger Rock AR-15 7.62x39 Bolt Carrier Group (BCG): Manufacturer: Tiger Rock Color: Black Finish: Ultra Hard Nitride Fabric/Material: Heat Treated Steel Carrier Material: 8620 Steel Bolt Material: 9310 Steel Caliber: 7.62x39mm Gun Make: AR Platform Gun Model: M16 AR-15 Hand: Right Features of Tiger Rock AR-15 7.62x39 Bolt Carrier Group BCG: M16 Style (Full Auto); Precision Machined; Shot Peened MPI Bolt - 9310 material; 8620 Gas Carrier Package Contents: Tiger Rock AR-15 7.62x39 Bolt Carrier Group What firearm models does the manufacturer say Tiger Rock AR-15 7.62x39 Bolt Carrier Group (BCG) is compatible with? The manufacturer suggests that Tiger Rock AR-15 7.62x39 Bolt Carrier Group (BCG) is compatible with AR-15 M16Tiger Rock BCG-AK: AR-15 7.62x39 Bolt Carrier Group Black Nitride 9310 Bolt