Sons of Liberty Gun Works Bolt Carrier Group 223 Remington/556NATO - Nickel Teflon CoatedSons of Liberty goes to show that in order to make the best products in the industry, you don't have to add bells and whistles. It takes consistently delivering a product that performs to a professional standard. That is what SOLGW does with their milspec line of components.Bolt: Precision machined from Carpenter Technology No. 158 chrome-nickel alloy Heat treated per mil-spec, Shot peened per ASTM B851/SAE AMS2430S, Vibratory tumbled Individual high pressure/proof (HP) test Full Auto test fired at assembly Individual magnetic particle inspection ASTM E1444/E1444M (MP) Nickel Teflon Coated Markings deep laser engraved (SP=Shot Peened, HP=High Pressure Tested, MP=Magnetic Particle Inspection.)Extractor: Precision machined from 4340 tool steel alloy per SAE AMS6415T/AMS6484D (vs 4140) Heat treated Shot peen per ASTM B851/SAE AMS2430SExtractor Retaining Pin: Precision machined and ground S7 Tool Steel Heat treated per ASTM A681-08 Shot peened per mil-spec print Manganese phosphateExtractor Spring: Tactical Springs/Sprinco 5 coil, ASTM Grade A401 Chrome Silicon wire stock Heat treated Stress relieved, Molybdenum-Disulfide infused Cryogenic processed (Hidden post winding) Mil-spec black insert/synthetic elastomer extractor buffer (nitrile-butadiene, shore hardness 80+/-5 durometer per MIL-PRF-6855)Ejector: S7 Tool Steel Heat treated per ASTM A681-08 Shot peened per Mil-Spec Nickel Teflon Coated Ejector Spring: Heat treated Mil SpecGas Rings: Standard stainless steel per Mil-Spec X3Carrier: Machined from AISI 8620 aircraft quality alloy per ASTM A108/A322-13 Full auto profile Heat-treated Carburized/strain relieved, hard chrome bore Precision ground gas key interface Sons of Liberty Battle Flag logo deep laser engraved Nickel Teflon CoatedGas Key: Machined from 4130 Chromoly steel alloy per ASTM A108/A322-13 Heat-treated; hard chrome internal Nickel Teflon Coated Permatex sealed Grade 8 hex screws torqued and staked Hidden per mil-specCam Pin: Precision machined 4340 Chromoly steel alloy per SAE AMS6415T/AMS6484D Heat-treated/processed per mil-spec Nickel Teflon Coated Solid film lubricant applied and cured per mil-specFiring Pin: Precision machined 8640 steel alloy Heat treated/processed per mil-spec Hard chrome plateFiring Pin Retaining Pin: Precision machined from 1038 carbon steel Heat-treated/processed per mil-spec Manganese phosphate