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. Hand Right Twist 1:8" Action semi-auto Muzzle Muzzle Brake Safety Manual Thumb Series M5L Sights Optic Ready Caliber 5.56x45mm NATO Trigger Mil-Spec Capacity 30+1 Barrel Length 16" Receiver Material 7075-T6 Aluminum Stock Description Mil-Spec HM Barrel Description 4150 Chrome Moly Match Grade Metal Finish Group Blued/Black Stock Finish Group Black Barrel Length Range 16" to 16.99"