Proof Research PR10 Carbon Fiber 20in 308 Win Rifle Length Rifle Barrel 30cal 0.875GB 10 Twist 5/8 x 24. Through a unique manufacturing process these rifle barrels by Proof Research achieve both lightweight characteristics by weighing less and meeting functional specifications. One example of many of the practical applications of these Proof Research Rifle Barrels is the ability to forge a stronger-than-steel short-barreled impact weapon. While they are certainly lighter than steel barrels they will not absorb any additional weight. Proof Research barrels are the strongest and most durable of all the carbon fiber rifle barrels on the market. Get yours today and witness the difference a durable carbon fiber barrel can make in your shooting game. Specifications for Proof Research PR10 Carbon Fiber 308 Win Rifle Barrels: Manufacturer: Proof Research Color: Black/Silver Fabric/Material: Carbon Fiber Caliber: .308 Winchester Barrel Profile: Contour 0.875GB Gas System Length: Rifle Length Gas Block Journal Size-Diameter: .875 in Threads per Inch: 5/8x24 Barrel Twist Rate: 1-10 Flutes: No Condition: New Package Contents: Proof Research PR10 Carbon Fiber 308 Win Rifle Barrels Proof Research PR10C200300DBB10B308W: PR10 Carbon Fiber 20in 308 Win Rifle Length Rifle Barrel 30cal 0.875GB 10 Twist 5/8 x 24