Just as Dennis said...the easy way: Put your drill in a vise to keep it steady, put the Jag in the drill clamp, turn the drill on and use the file to grind it down. Should take less than a few minutes of time. Then polish the Jag on a polishing wheel, or keep it somewhat rough to grab the cleaning patch. If you want to deepen the grooves while in the drill, use a smaller file inside the grooves. Done this many times.