The radical firearms 16" socom 5.56mm ar rifle uses mil-std upper and lower receivers along with our 15" mhr free-float rail system for increased accuracy, keeping your hands cool, and giving you plenty of room for accessories.It utilizes a 4140 chrome moly vandium barrel with a a2 flash hider and a b5 bravo stock.Metal Finish: Black Hardcoat Anodized/Black MeloniteAction: Semi-AutoCaliber: 5.56x45mm NATOBarrel Length: 16"Capacity: 30+1Safety: Manual ThumbStock Description: 6 Position B5 Bravo AdjustableMuzzle: A2 Flash HiderReceiver Material: 7075-T6 AluminumSights: Optic ReadyBarrel Description: Chrome Moly VanadiumTwist: 1:7"Barrel Length Range: 16" to 16.99"Hand: RightStock Finish Group: BlackMetal Finish Group: Blued/Black