Proof Research PR15 PXT Carbon Fiber Barrel Features The Proof Research PR15 PXT Carbon Fiber Barrel is built for the AR-15 platform and chambered in 6mm ARC combining a carbon fiber outer wrap with a precision machined barrel to reduce weight without sacrificing rigidity. At 20 inches long with a rifle plus length gas system profile the barrel is well suited to extracting the ballistic potential of the 6mm ARC cartridge in a precision oriented build. A 1:7.5 twist rate stabilizes the heavier for caliber bullets that make 6mm ARC effective at extended range giving shooters confidence in bullet selection for long range work. Five grooves are cut into the bore to engage the bullet consistently supporting the accuracy Proof Research barrels are built around. The barrel s standard diameter profile measures 0.750 inches a common dimension that works with a wide range of handguards and gas block options already on the market. A threaded muzzle in the 5/8x24 pattern accepts standard muzzle devices compensators or suppressor mounts without requiring custom machining. Because the barrel is wrapped in carbon fiber rather than relying solely on a heavier steel profile the overall weight savings make a noticeable difference in a complete rifle s balance and handling. For AR-15 builders chambering 6mm ARC who want to shave weight while keeping precision rifle accuracy the Proof Research PR15 PXT Carbon Fiber Barrel is available for sale at GrabAGun. Proof Research PR15 PXT Carbon Fiber Barrel Specifications Manufacturer: Proof Research Model: PR15 PXT Carbon Fiber Barrel Caliber: 6mm ARC Gun Platform: AR-15 Barrel Material: Carbon Fiber Barrel Type: Rifle +1 Length Twist: 1:7.5 Diameter: .750 Grooves: 5 Thread Pattern: 5/8x24 Barrel Length: 20 Weight: 1 lb. 12 oz. Available At: GrabAGun