Barrel: 7" 4150V Chrome Moly vanadium steel, nitride treated for durability and chambered in 5.56 NATO with a 1 in 7" twist. Pistol length gas barrel is finished off with a Magpul MOE M-Lok carbine length handguard, a low profile gas block and a patent pending PSA muzzle device designed to hold the handguard endcap in place. Upper: Forged 7075-T6 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. Shot-peened, mil-spec Carpenter No. 158A(R) steel bolt. 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. Lower: These forged lowers are quality made using 7075-T6 aluminum and are marked "MULTI" for caliber. Finish is hardcoat anodized. Pistol 7075-T6 buffer tube is hardcoat anodized and is fitted with a H&R HAR-15 Adjustable Pistol Stabilizing Blade.