Hm defense's defender m5 rifle features a hm monobloc barrel with an integral machined gas block.The 4150 chromoly barrel also features a mid-length gas system and is match grade, tripled honed, and button rifled.The defender m5 also utilizes a 12" free-float handguard with 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+1Safety: ManualStock Description: Mil-Spec HMMuzzle: Muzzle BrakeReceiver Material: 7075 T6 AluminumSights: None, Optic ReadyBarrel Description: 4150 Chrome MolyTwist: 1:8"Barrel Length Range: 16" to 16.99"Hand: RightStock Finish Group: BlackMetal Finish Group: Blued/Black