Milspec Carpenter No. 158® steel bolt. Shot Peened Bolt. High pressure tested. Mag particle inspected. Chrome Lined Carrier (AUTO). Chrome Lined Gas Key. Gas Key Hardened to USGI Specifications. Firearms, Rifles, Tactical, Semi-Auto, Accessories, Gun Parts, Rifle Parts, Uppers, Bolt Carrier Groups, Firearms Accessories, Shooting Sports, Camping Gear, Camping Essentials, Camping Accessories, Camping Aesthetic, All things Camping, Camping Hacks, Camping Outdoor, Survival Tools!