The Guardian F5 rifle features an all HM match grade defense barrel. It also features a custom HM Defense 10 3/8 inch, free float 1913 Picatinny rail that is compatible with the Magpul M-Lock mounting system. Some other components of the rifle include an M16 bolt carrier group with patented HMB bolt and mil-spec components, including the trigger & fire control group, charging handle and buffer tube/spring. Also a custom trigger guard, CNC machined muzzle brake, and steel gas block. Hand Right Twist 1:7" Action semi-auto Muzzle Muzzle Brake Series F5 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 Chromoly Steel Metal Finish Group Blued/Black Stock Finish Group Black Barrel Length Range 16" to 16.99"