Hm defense's defender m5 rifle features a hm monobloc 4150 chromoly, match grade barrel with an integral machined gas block and is tripled honed and button rifled.The defender m5 utilizes a 15" free-float 1913 picatinny rail and is compatible with magpul m-lok mounting system.To finish off this tactical firearm is a mil-spec hm stock and enhanced grip.Metal Finish: Black Hardcoat AnodizedAction: Semi-AutoCaliber: 5.56x45mm NATOBarrel Length: 16"Capacity: 30+1Trigger: Mil-SpecSafety: Manual ThumbStock Description: Mil-Spec HMMuzzle: Muzzle BrakeReceiver Material: 7075-T6 AluminumSights: Optic ReadyBarrel Description: 4150 Chrome Moly Match GradeTwist: 1:8"Barrel Length Range: 16" to 16.99"Hand: RightStock Finish Group: BlackMetal Finish Group: Blued/Black