The radical firearms rpr 16" socom 5.56mm ar rifle uses mil-std upper and lower receivers along with our 15" rpr free float rail system for increased accuracy, keeping your hands cool and giving you room for accessories.Featuring a b5 grip type 23 pistol grip; b5 bravo stock with 6 positions; carbine mil-std buffer tube; a2 flash hider and a chrome moly vanadium threaded barrel.Action: Semi-AutoCaliber: 5.56x45mm NATOBarrel Length: 16"Trigger: Mil-SpecStock Description: B5 Bravo 6 PositionMuzzle: A2 Flash HiderReceiver Material: AluminumSights: NoneBarrel Description: Steel ThreadedTwist: 1:7"Barrel Length Range: 16" to 16.99"Hand: Right HandStock Finish Group: BlackMetal Finish Group: Blued/Black