Flex-Hone, made by Brush Research Manufacturing, has honing tools designed to finish and polish barrels, chambers or forcing cones. Midway USA has most all gauges in stock for around $35 Bucks. Did a vintage long tang Browning Superposed, that never could get the chamber to look right. After about 15 minutes, looks brand new again. They are just like doing an old 6-pack Chevy In-Line for rings, same tool and methods, Honing Oil, N a Drill Motor, but it's tiny.