Whew, ya'll makin' my poor, ignerrant head spin!
I'm gonna call USFA and see if I can find someone to talk to, as Del suggested. I've been avoiding that because I don't want to go through the PITA of boxing, shipping, and especially waiting for the return, if the rodeos need to be sent back. But, ya gotta do what ya gotta do.
Mako touched on something I mentioned doing a while back--switching powders. I have some SWISS 3f, and I may try it out. But I also suspect that if it was a pressure problem, I woulda seen an improvement from 1.9cc's to 2.2cc's (about 5 grain-by-weight difference in load). There wasn't really an improvement. I've tried different cases, different sizing, different loads, and it ain't workin'. The field's gettin' narrow.
I measured the headspace in my USFA Premium .45 LC. It was .005. That's less than half the distance of the rodeos. Personally, I believe the soft "push" of black powder (vs. the sharp recoil of smokeless. thanks, Del) combined with the extra long distance of the headspace (thanks, John Boy), is the culprit.
Once again, thanks to all of ya'll. I've learned a lot from this discussion!