Because you asked the question I can only assume(yeah,I know) your not REAL familiar with attatching a jag to a rod,it's not just glue and push on. Get the 42" with tip installed and just cut to length. Use the rod from your gun as a pattern,I'd leave just a touch more length then ajust as needed. You may have to sand the rod a bit to fit also,they have a tendency to be a touch thick,not much though.