JP Enterprises Supermatch Barrel With Headspaced Jp Enhanced Bolt 300 Blackout Chamber 16in Black. 300 AAC Blackout Weight: 1.75 lb Features of JP Enterprises Supermatch Barrel With Headspaced Jp Enhanced Bolt 300 Blackout Chamber Includes a JP EnhancedBolt individually head-spaced to the barrel for flawless fit and function. Chamber: .300 AAC Blackout Length: 10.5" Gas System: Pistol-length Twist: 1:8 button rifled Contour: .740 in front of gas block Diameter at Gas Block: .750 Muzzle Threads: 5/8-24 TPI Material: 416R Stainless Finish: Machined Stainless Weight: 20 oz. Package Contents: JP Enterprises Supermatch Barrel With Headspaced Jp Enhanced Bolt 300 Blackout Chamber JP Enterprises JPSM300BLK-16L8P-BT: Supermatch Barrel With Headspaced Jp Enhanced Bolt 300 Blackout Chamber 16in Black