JE Machine Tech AR-15 .223 Bolt Carrier Group BCG Chrome Lined Nitride Coating MPI Certified Mil-Spec Black. 223 Bolt Carrier Group (BCG): Manufacturer: JE Machine Tech Color: Black Finish: Chrome Lined Caliber: .223 Remington Gun Model: AR-15 Hand: Right Additional Features: Nitride Coating Features of J&E Machine Tech AR-15 .223 Bolt Carrier Group BCG: High pressure and Magnetic Particle tested Chrome lined gas key and Shot-Penned bolt Gas key is stalked per Mil's Spec Package Contents: J&E Machine Tech AR-15 .223 Bolt Carrier Group What firearm models does the manufacturer say J&E Machine Tech AR-15 .223 Bolt Carrier Group (BCG) is compatible with? The manufacturer suggests that J&E Machine Tech AR-15 .223 Bolt Carrier Group (BCG) is compatible with AR-15JE Machine Tech PS-BCG3: AR-15 .223 Bolt Carrier Group Chrome Lined Nitride Coating MPI Certified Mil-Spec Black