Proof Research AR-10 .308 Winchester Threaded AR Barrel Standard Standard 18 in Gas Length Rifle 10 Twist Pxt 1.15 Weight Carbon. PXT - PROOF Exponential Twist - is a complete rethinking of conventional rifling geometry and twist progression engineered to reduce engraving force minimize throat erosion and create a smoother transition as the projectile engages the rifling. Specifications for Proof Research AR-10 .308 Winchester Threaded AR Barrel: Manufacturer: Proof Research Color: Carbon Caliber: .308 Winchester Barrel Profile: Standard Barrel Twist Rate: 1-10 Gun Make: AR Platform Gun Type: Rifle Package Contents: Proof Research AR-10 308Win Threaded AR Barrel What firearm models does the manufacturer say Proof Research AR-10 .308 Winchester Threaded AR Barrel is compatible with? The manufacturer suggests that Proof Research AR-10 .308 Winchester Threaded AR Barrel is compatible with AR-15 AR-10Proof Research 156094: AR-10 .308 Winchester Threaded AR Barrel Standard Standard 18 in Gas Length Rifle 10 Twist Pxt 1.15 Weight Carbon