Hardened steel, muzzle crowning tool cuts a slight (11° less than square) target chamfer on barrels. Gives good rifling protection without going too deep. 90° - 11° = 79°, hence the name. Eight, precision-machined flutes give smooth, chatter-free cuts to help eliminate extra lapping or stoning. ¼"-20 thread fits Brownells muzzle chamfering handles. Use with our muzzle pilots to ensure precise alignment with your bore. Available in ½" and ¾" diameters to accommodate most rifle/handgun barrel diameters.