I have a .45 caliber TC Hawken percussion barrel laying around in my "shop"...was a freebie from a friend some years back. I won by auction a Hawken stock with triggers, all the metal and brass on it, including the tang with two screws (but no lock). Then I discovered there is a 3-screw Hawken tang. Besides the extra screw...what is the difference and does it make any difference as to whether the barrel will fit or not?