The K&M Premium Flash Hole Uniformer has a carbide cutting head that allows the brass chips to free flow from the cutter head while chamfering the flash hole at the case web.The tip of the tool has a gentle taper to help enter the flash hole."Premium" tool chamfer cut depth is controlled from the case web. So once the tool bottoms on the case web the cutting action is done regardless of overall case length variation.Insert the tool through the mouth of the case into the flash hole and grip the case with your hand. The tool shaft diameter guides the tool through the case neck to maintain the centerline of the cartridge. Rotate the tool handle with the other hand until you no longer feel the tool cutting.