Barrel: Nitride finished 4150V chrome moly vanadium 16" barrel. Chambered in 5.56 NATO, with a 1:7 twist, M4 barrel extension, and a Mid-length gas system. The barrel is finished off with a 13.5" Hex Full Picatinny M-Lok Free Float Rail, .750 low profile gas block, and A2 flash hider.Upper: Forged 7075-T6 A3 AR upper is made to MIL-SPECS and hard coat anodized for durability. These uppers are made for us right here in the USA by a mil-spec manufacturer.Bolt: Full-auto profile bolt carrier group. Milspec Carpenter No. 158A(R) steel bolt, Shot Peened, High pressure tested, Mag particle inspected, Gas Key Hardened to USGI Specifications, Fastened with Grade 8 screws, and Staked Per Mil-Spec. The carrier is 8620 steel.Build Kit: PSA EPT MOE CTR Lower Build Kit, Flat Dark EarthIncludes PSA Classic Stock, Classic A2 Pistol grip, and milspec trigger guard, Palmetto State Armory Lower Parts Kit and Mil-Spec diameter 6-position buffer tube assembly.Everything you need to finish your stripped lower!Includes: MagpulA(R) MBUS Rear Sight, Black