Proof Research Barrel Features The Proof Research Barrel wraps a precision-rifled steel liner in a carbon fiber sleeve cutting substantial weight from the front end of an AR10 build without sacrificing the accuracy of a quality steel barrel. This weight savings makes a real difference in offhand handling and reduces fatigue during long days at the range or in the field. The 1:10 twist rate is well suited to a wide range of .308 Win bullet weights giving shooters flexibility in load selection. Five-groove rifling and a rifle-length gas system profile support consistent repeatable accuracy shot after shot. At 18 inches with a .875 diameter this standard contour barrel strikes a balance between weight savings and barrel stiffness for sustained accuracy. The 5/8x24 threaded muzzle accepts a brake compensator or suppressor letting shooters configure the end of the barrel to match their intended use. Proof Research barrels are built for shooters who demand match-level accuracy without the weight penalty of a traditional steel barrel. For AR10 owners looking to upgrade their factory barrel this Proof Research option delivers a proven combination of light weight and precision. Proof Research Barrel Specifications Manufacturer: Proof Research Model: Barrel Caliber: .308 Win Compatible Hosts: AR10 Material: Carbon Fiber Barrel Length: 18 Twist Rate: 1:10 Diameter: .875 Grooves: 5 Thread Pattern: 5/8x24 Barrel Description: Standard Rifle Length Available At: GrabAGun