The Widening Wheel thread has plenty of information on this topic, so I'd take a look there for more info:
http://zilvia.net/f/showthread.php?t=327620
To answer your questions, I just want to clarify. Are the barrels the originals or new? If original, are they bent at all? It is possible, although I haven't had it happen yet, the new powder coat is too thick. It should be a pretty tight fit to begin with and powder can be a few thousandth of an inch thick.