Proof Research Impact Precision 737 .308 Winchester Threaded Rifle Barrel 16.5 in Sendero 10 Twist Pxt 5/8-24 Thread 2.1Weight 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 Impact Precision 737 .308 Winchester Threaded Rifle Barrel: Manufacturer: Proof Research Color: Carbon Caliber: .308 Winchester Barrel Twist Rate: 1-10 Barrel Profile: Sendero Firearms Threads Per Inch: 5/8x24 Gun Make: Impact Precision Gun Model: Impact Precision 737 Gun Type: Rifle Package Contents: Proof Research Impact Precision 737 308Win Threaded Rifle Barrel What firearm models does the manufacturer say Proof Research Impact Precision 737 .308 Winchester Threaded Rifle Barrel is compatible with? The manufacturer suggests that Proof Research Impact Precision 737 .308 Winchester Threaded Rifle Barrel is compatible with Impact Precision 737Proof Research 156315: Impact Precision 737 .308 Winchester Threaded Rifle Barrel 16.5 in Sendero 10 Twist Pxt 5/8-24 Thread 2.1Weight Carbon