Gotbuck

The "witness mark"... if you shorten your current rod to install the TC Super Jag and you shorten it on the end that you normally put down the muzzle - your witness mark will not move if you end up with the same total length...

But, with all that said It might be wiser to install the new jag on a new rod, then you will always have the original - which might come in handy. Especially if you have 'Chap's' problem and leave them laying around in the woods....