Member's Area - Machining & Subclass -
Manufacturing Methods - Button Rifling

Reduced Potential for Subclass Carryover

Button rifling – A process in which grooves are pressed into the interior of the barrel using a tool called a button. The button is made from solid carbide, is larger than the reamed bore, and is either pulled or pushed through the bore, depending upon the type of machinery used.

Due to the fact that button rifling primarily displaces/compresses the metal inside the barrel to form the rifling, many of the circular marks from the drilling and/or reaming are not obliterated. As with those processes, the tool marks remaining are perpendicular to the bore therefore imparting individual characteristics on the bearing surface of a bullet (see drilling, reaming). One other factor contributing to the creation of individual characteristics on a bullet surface, is that although this method is a swaging process, there is some cutting occurring at the intersection of the button and the shoulder of the land/groove (see photo). This cutting creates metal buildup which in turn can impart a unique pattern on the bullet surface.