TACTICAL AMBUSH BCG Bolt carrier group (auto version) for your AR15, M16, or M4. Parkerized exterior. Machined to USGI specifications. This M16/M4 carrier includes the proper Mil-Spec gas key heat treated per GI specifications. Gas key is secured and chrome lined also the carrier is chrome lined via USGI domestic mfg Grade 8 fasteners and properly staked per Mil-Specs. These properly hardened parts insure a strong staking and proper gas system functioning. The bolt assembly is machined from the correct Mil-Spec Carpenter No. 158® steel, shot peened for increased strength, includes tool steel machined extractor and ejector, Extractor Spring, and is HPT (High Pressure Tested) and MPI (Magnetic Particle Inspected). Prior to shipping, all Bolt Carrier Groups are test fired for function