Proof Research Zermatt Origin 25 Creedmoor Threaded Rifle Barrel Sendero 22 in 7.5 Twist Pxt 5/8-24 Thread 3.2 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 Zermatt Origin 25 Creedmoor Threaded Rifle Barrel: Manufacturer: Proof Research Caliber: .25 Creedmoor Barrel Twist Rate: 1-7.5 Firearms Threads Per Inch: 5/8x24 Gun Make: Zermatt Arms Gun Model: Zermatt Origin Gun Type: Rifle Package Contents: Proof Research Zermatt Origin 25Cm Threaded Rifle Barrel What firearm models does the manufacturer say Proof Research Zermatt Origin 25 Creedmoor Threaded Rifle Barrel is compatible with? The manufacturer says that Proof Research Zermatt Origin 25 Creedmoor Threaded Rifle Barrel is compatible with Zermatt OriginProof Research 157343: Zermatt Origin 25 Creedmoor Threaded Rifle Barrel Sendero 22 in 7.5 Twist Pxt 5/8-24 Thread 3.2 Weight Carbon