ODIN Works AR 15 Black Nitride Bolt Carrier Group BCG Black AR15 .223 ACC-.223 -BCG. e.) .223/5.56mm .300 Blackout Specifications for ODIN Works Bolt Carrier: Manufacturer: ODIN Works Color: Black Finish: Nitride Carrier Material: 8620 Steel Bolt Material: Steel Gun Model: M4 AR-15 Condition: New Last Chance: Yes Features of ODIN Works Bolt Carrier: Mil-Spec dimentions Bolt Carrier Group BCG Material: Case Hardened 8620 Steel Finish: Black Nitride. This advanced low friction coating minimizes the need for lubricants. Gas Key: 4130 Steel attached with Grade 8 hardware and properly staked into a milled valley to ensure proper positioning. Cam Pin: Hardened 4340 cam pin Firing Pin: Mil Spec firing pin made of 8740 steel center-less ground and Hard Chrome coated Bolt Assembly: The Bolt is true Mil Spec dimension and external surfaces are CNC ground after heat treat for a precision fit. Bolt Material: Case Hardened 9310 Steel. Finish: All Bolt components Black Nitride Extractor: 4340 Steel Mil Spec Extractor Spring O-Ring Combination MPI: Magnetic Particle Inspected HPT: High Pressure Test Package Contents: ODIN Works Bolt Carrier What firearm models does the manufacturer say ODIN Works Bolt Carrier is compatible with? The manufacturer says that ODIN Works Bolt Carrier is compatible with AR-15 M4ODIN Works ACC-.223 -BCG: AR 15 Black Nitride Bolt Carrier Group Black AR15 .223