Proof Research Impact Precision 737 6.5mm Creedmoor Threaded Rifle Barrel 26 in Competition 7.5 Twist Pxt 5/8-24 Thread 7.5Weight Silver. 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 6.5mm Creedmoor Threaded Rifle Barrel: Manufacturer: Proof Research Caliber: 6.5mm Creedmoor Barrel Twist Rate: 1-7.5 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 6.5Cm Threaded Rifle Barrel What firearm models does the manufacturer say Proof Research Impact Precision 737 6.5mm Creedmoor Threaded Rifle Barrel is compatible with? The manufacturer suggests that Proof Research Impact Precision 737 6.5mm Creedmoor Threaded Rifle Barrel is compatible with Impact Precision 737Proof Research 155745: Impact Precision 737 6.5mm Creedmoor Threaded Rifle Barrel 26 in Competition 7.5 Twist Pxt 5/8-24 Thread 7.5Weight Silver