8.6 BLK barrel caliber; barrel nut included; Thread protector included; Magnetic Particle Inspected; M18x1.5 muzzle thread, tapered shoulder (adapter included); 11 degree Target Crown; With barrels employing an impressive 1:3 twist rate, 8.6 BLK channels rotational energy to increase energy on-target; It is fully stress-relieved, air-gauge tested; Constructed of 416-R Stainless Steel; It is machined from raw bar stock in Faxon's greater Cincinnati Facility