Dark Storm Industries DS-15 5.56 Bolt Carrier Group BCG Nickel Boron. 223 5.56 or .300 Blackout Specifications for Dark Storm Industries DS-15 5.56 Bolt Carrier Group (BCG): Manufacturer: Dark Storm Industries Fabric/Material: Steel Carrier Material: 8620 Steel Caliber: 5.56x45mm NATO Gun Make: AR Platform Gun Model: AR-15 Hand: Right Features: Bolt Carrier / Gas Key "M-16" Style 8620 Cromoly Steel Phosphate Finish Hard Chrome Lined Bolt Chamber Hard Chrome Lined Gas Key Grade 8 Torqued and Staked Gas Key Hardware Bolt 5.56 Bolt Head Assembly Carpenter 158 Cromoly Steel Phosphate Finish Shotpeened MPI Magnetic Particle Inspected S7 Tool Steel Extractor 17-4 Heated Treated Stainless Steel Firing Pin Package Contents: Dark Storm Industries DS-15 5.56 Bolt Carrier Group What firearm models does the manufacturer say Dark Storm Industries DS-15 5.56 Bolt Carrier Group (BCG) is compatible with? The manufacturer suggests that Dark Storm Industries DS-15 5.56 Bolt Carrier Group (BCG) is compatible with AR-15Dark Storm Industries DSI-BCG-556-NIB: DS-15 5.56 Bolt Carrier Group Nickel Boron