Barrel: Chrome-moly vanadium steel, phosphate coated, chrome lined barrel chambered in 5.56 NATO, with a 1:7 twist rate, M4 barrel extension, and a carbine-length gas system. The tapered profile barrel is finished off with a PSA 9" Guardsman Hex Full Picatinny M-Lok free-float rail, pinned low-profile gas block, and A2 flash hider. Upper: Forged 7075-T6 A3 AR upper is made to MIL-SPECS and hard coat anodized black for durability. Featuring a mil-spec finish, these uppers are made for us right here in the USA by a mil-spec manufacturer. Bolt Carrier Group: Full-auto profile bolt carrier group. Shot-peened, HPT, mil-spec Carpenter 158 steel bolt. Sprinco gas rings. Gas Key Hardened to USGI Specifications, Fastened with OCKS screws, and Staked Per Mil-Spec. The carrier is an 8620 steel M-16 full-auto profile. Phosphate coated and chrome lined. Lower: These forged lowers are quality made using 7075-T6 aluminum and are marked "MULTI" for caliber. The finish is hard coat anodized. Pistol 7075-T6 buffer tube is hard coat anodized and is fitted with an H&R HAR-15 Adjustable Pistol Stabilizing Blade, Magpul MOE Grip, and PSA "Guardsman" Flat Bow Single Stage trigger and Ambi Safety.