A tool having a series of cutting edges (buttons) of slightly increasing height is used to cut spiral grooves in a barrel. All grooves are cut with a single pass of the broach. Each button is the equivalent of one set of passes through the barrel with the cutter at a set depth using cut rifling. The buttons on the broach grow in diameter approximately .0005” with each proceeding button, which is the same amount the cut rifling tool is raised after making a cut in each groove. The broaching tool pulled through the barrel one time with multiple buttons, each comprised of a series of cutters, is the equivalent of making multiple passes through the barrel with cut rifling. The images below are of a gang broach. Photographs courtesy of Scott Doyle –http:// www.firearmsid.com
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