Proof Research Terminus Apollo 22 Creedmoor Threaded Rifle Barrel Sendero 18 in 8 Twist Pxt 5/8-24 Thread 2.8 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 Terminus Apollo 22 Creedmoor Threaded Rifle Barrel: Manufacturer: Proof Research Color: Carbon Caliber: .22 Creedmoor Projectile Caliber: .224 Caliber Barrel Material: Stainless Steel Barrel Twist Rate: 1-8 Barrel Profile: Sendero Firearms Threads Per Inch: 5/8x24 Gun Make: Terminus Gun Model: Terminus Apollo Gun Type: Rifle Package Contents: Proof Research Terminus Apollo 22Cm Threaded Rifle Barrel What firearm models does the manufacturer say Proof Research Terminus Apollo 22 Creedmoor Threaded Rifle Barrel is compatible with? The manufacturer suggests that Proof Research Terminus Apollo 22 Creedmoor Threaded Rifle Barrel is compatible with Terminus ApolloProof Research 156391: Terminus Apollo 22 Creedmoor Threaded Rifle Barrel Sendero 18 in 8 Twist Pxt 5/8-24 Thread 2.8 Weight Carbon