Barrel: 416R stainless steel barrel. Chambered in 223 Wylde, with a 1:7 twist rate, M4 barrel extension, and a rifle-length gas system. Barrel is finished off with a PSA 15" Lightweight M-Lok free float rail, .750" low-profile gas block, and an A2-style flash hider. Upper: Forged 7075-T6 aluminum A3 AR upper is made to MIL-SPECS and hard coat anodized black 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. 8620 steel M-16 profile carrier is chrome lined and phosphate coated. Included: Magpul MBUS Sight Set, Black