Spikes tactical complete phosphate m-16 bcg features phosphate coating inside and out (bolt, carrier and gas key), laser engraved with st spider logo, mil spec carrier and full auto m-16.Includes mil-spec extractor, mil-spec gas key, firing pin, cam pin and retaining pin.Finish: Nickel BoronType: Bolt Carrier GroupModel: Bolt Carrier GroupSize: 223 Remington/5.56 NATOMaterial: SteelBolt Type: Full AutoHand: 11.60 oz