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. Action Semi-Auto Caliber 5.56x45mm NATO Barrel Length 16" Capacity 30+1 Trigger Mil-Spec Safety Manual Stock Mil-Spec HM Metal Finish Black Hardcoat Anodized Muzzle Muzzle Brake Receiver Material 7075-T6 Aluminum Sights None, Optic Ready Barrel 4150 Chrome Moly Match Grade Twist 1:8" Hand Right Stock Finish Group Black Metal Finish Group Blued/Black Left Hand Model No Youth Model No UPC 854164007180