Gives the forcing cone a gentle taper that reduces recoil and improves shot patterns. Provides a smooth transition for the shot cup, with less pellet deformation, for greater pattern density. Spiral flutes give a chatter-free cut on all types of barrel steel.The long shank lets you alter most barrels using only a large tap handle to turn the reamer. Mfg: Manson Precision SPECS: M-7 High Speed Steel. 8-flute, right hand cut with left hand spiral. 9" (22.9) long, 3-½" (8.9cm) shank, 7/16" square.