Available in 20 or 16 4150 chrome moly steel barrels FNC treated for maximum durability and longevity - 20 version features a Hunter stock with recoil pad - 16 version features a B5 Sopmod stock - New proprietary 450 Bushmaster twin port muzzle brake - Magpul Grip - Mil Std Upper & Lower - SquareDrop rail for free-floated accuracy and accessory mounting ease - Improved trigger control with ALG Defense fire control group - Caliber: .450 Bushmaster - Magazine Capacity: 5