JP Enterprises Supermatch Barrel With Headspaced Jp Enhanced Bolt 5.56 10.5in Silver. 56X45 Chamber Carbine-Length Port Position Stainless Specifications for JP Enterprises Supermatch Barrel With Headspaced Jp Enhanced Bolt 5.56: Manufacturer: JP Enterprises Caliber: 5.56x45mm NATO Features of JP Enterprises Supermatch Barrel With Headspaced Jp Enhanced Bolt 5.56 Includes a JP EnhancedBolt individually head-spaced to the barrel for flawless fit and function. Chamber: 5.56 Length: 10.5" Gas System: Carbine Twist: 1:7 button rifled Contour: .750 under hand guard/.740 in front of gas block Diameter at Gas Block: .750 Muzzle Threads: 1/2-28 TPI Material: 416R Stainless Finish: Machined Stainless Weight: 22 oz. Package Contents: JP Enterprises Supermatch Barrel With Headspaced Jp Enhanced Bolt 5.56 JP Enterprises JPSM556-10.5L7C: Supermatch Barrel With Headspaced Jp Enhanced Bolt 5.56 10.5in Silver