Bolt - Carpenter 158 heat-treated, shot peened and magnetic particle inspected. Manufactured to government drawings; Milspec gas rings. NiB-X coated (40% more wear-resistant than chrome); Extractor - Manufactured, heat treated, and hardened per government drawings; Black extractor buffer and heavy-duty spring. NiB-X coated; Firing Pin - Manufactured, heat-treated, hardened, chromed and certified per government drawings; Carrier - AR-15 or M16 style (heavy weight), 8620 material, heat treated and case hardened; Manufacturing tolerances on inside diameters tightly controlled; NiB-X coated; Gas Key - Hardened to USGI Specifications and attached using grade 8 hardened fasteners; NiB-X coated; Staked per military specifications; Cam pin - Manufactured, heat treated, hardened and certified per Government drawings; NiB-X Coated. Hammer - Manufactured, heat treated, hardened and certified per government drawings; Made in USA