Centurion Arms Threaded Rifle Barrel MK12 18 in 416R Stainless Steel 1/2x28 1-7 Twist Rifle Length Stainless NSN 9305.20.9000. S. government to give Special Operations forces the best possible weapon system. Troops who have carried these AR15 Barrels from Centurion Arms give them high marks for reliability and accuracy. Centurion Arms MK12 Crane Spec. Rifle Barrels are manufactured from 416R stainless steel with a stainless finish. Get special ops quality when you upgrade to the Centurion Arms MK12 18 inch Rifle Barrel. Specifications for Centurion Arms MK 12 Threaded Rifle Barrel: Manufacturer: Centurion Arms Color: Stainless Finish: Stainless Fabric/Material: 416R Stainless Steel Barrel Length: 18 in Barrel Profile: MK12 Gas System Length: Rifle Length Threads per Inch: 1/2x28 Barrel Twist Rate: 1-7 Barrel Material: 416R Stainless Steel Gun Make: Century Arms Weight: 2.4 oz 2.4 lb Features of Centurion Arms MK 12 Threaded Rifle Barrel: Barrel Extension: M4 Feed Ramps Chamber: Optimized for use with MK262 (Black Hills 77gr equivalent) Contour: for use with OPS inc. Centurion Arms barrels serve as HBAR barrels Centurion Arms barrels require no further break in Requires gunsmith installation Package Contents: Centurion Arms MK 12 Threaded Rifle Barrel Centurion Arms MK12B: Threaded Rifle Barrel MK12 18 in 416R Stainless Steel 1/2x28 1-7 Twist Rifle Length Stainless NSN 9305.20.9000