The WMD BCG is precisely machined from high-grade steel to M16 specs before receiving WMD Gun's proprietary NiB-X nickel boron coating. This coating results in super-smooth action, extreme corrosion resistance, and a harder-than-chrome surface that prevents carbon fouling from adhering, making this an ideal choice for any one who does high-volume shooting. This set features a polished finish and does not include the hammer. If you are looking for a long lasting AR-15 bolt carrier group, the NiB-X BCG is guaranteed to keep your rifle running reliably for years to come. Features: Proprietary Nickel Boron coating Extremely durable and easy to clean Slick surface makes for an extremely smooth action Polished finish M16 cut Does not include hammer Carrier Steel: 8620 and heat treated Bolt Steel: Carpenter 158 and heat treated Firing Pin: Hardened and chromed Gas Key: Hardened and staked per military standards WMD Guns has established a reputation of excellence based on extensive firearms and defense industry experience, plating expertise, and gunsmithing capabilities. They are innovators in nickel boron products for the firearms industry and the sole source of the NiB-X nickel boron coating process. SPECIFICATIONS: Bolt FinishNickel Boron Bolt MaterialCarpenter 158 Steel BrandWMD Guns Caliber Gauge5.56 NATO Carrier FinishNickel Boron Carrier Material8620 Carpenter Steel Carrier StyleM16 Bolt Carrier High Pressure TestedUntested Magnetic Particle InspectMagnetic Particle Inspected Platform AR-15 Weight 12 Oz