Bear Creek Arsenal's .458 SOCOM/.450 Bushmaster bolt carrier groups (BCGs) are Magnetic Particle Inspected (MPI) to ensure high performance. BCA's .458/.450 BCG is made with durable 9310 Steel and compatible with both all Rear Charging 450 Bushmaster and .458 SOCOM uppers; the gas key is also staked from the side for enhanced durability. Includes Bolt, Bolt Carrier, Extractor Pin, Firing Pin, and Cam Pin. Use a Bear Creek Arsenal BCG for your next AR-15 build and experience high performance at a lower cost! Specifications: Brand: Bear Creek ArsenalCaliber / Guage: .450 / .458Carrier Style: StandardPlatform: AR-15Bolt Finish: ParkerizedBolt Material: 9310 SteelCarrier Finish: Black NitrideGas Key: StakedMagnetic Particle Inspection: Yes {{widget type="Magento\Cms\Block\Widget\Block" template="widget/static_block/default.phtml" block_id="42"}} It is the responsibility of the consumer to ensure all state, local, federal, and ITAR regulations are followed