.225/5.56 NATO AR15/M16 BCG Engineered to reduce carrier tilt and friction inside upper receiver Materials, tolerances, and coatings are used to meet or exceed milspec standards 9310 Hardened Bolt, Shot peened 8620 Billet machined and hardened carrier 4130 steel gas key — Grade 8 hardware with proper staking methods Weight 11.4oz Black Nitride Finish 100% made in the USA Limited Lifetime Midwest Industries Warranty Mfg: Midwest Industries, Inc.
