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: 5.56mm Bolt Carrier Group is Nickel Boron coated and features a 9310 bolt. The gas key is hardened and secured with Grade 8 fasteners, and is staked per Mil-Spec. Included: Magpul MBUS Sight Set, Black