Barrel: Chambered in 5.56 NATO with a 1:7 twist rate, M4 barrel extension, and a carbine gas system this barrel features a Nitride finish for accuracy and durability. The barrel is finished off with a PSA 10.5" Lightweight M-Lok Free Float Rail, .750 low-profile gas block, and A2 flash hider. Upper: Forged 7075-T6 A3 AR upper is machined to MIL-SPECS and hard coat anodized. Uppers include forward assist and dust cover. 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.Lower: This forged lower is quality made using 7075-T6 aluminum and is marked "MULTI" for caliber. The finish is hard coat anodized. Finished with an A2 Classic Grip, H&R HAR-15 Black Adjustable Pistol Stabilizing Blade, and 6 position 7075 buffer tube. The fire control group is a PSA mil-spec single-stage assembly.