Quick update fellas. Oh, the joys of replica parts. I received a replacement set of 580s from WSO and they were the exact same way as my first set. Since my first set already had one of the little rings snap out I decided, what the hell, I might as well snap all of them out and give it a try. Can't hurt. Sure enough, now they fit just fine with my fat bars but I have a new problem. They rattle like hell because those little loops are no longer there to hold them tightly into position.
Any suggestions on what I can stuff inside there to keep them from sounding like miniature rattle snakes on my wrist? I am going to try closing up the clam shell a little bit to get them back into the original shape. Maybe that will help a bit. Can I stuff a wadding of cotton or something in there, too, to absorb some of the free play and to muffle the sound?