I did try cleaning the chamber, but it made no difference, and wasn't really that dirty anyway.
I do really think the factory stuff might be over pressure, at least the brass cased stuff I got, the primers do look pretty gnarly.
I left some posts on here about my testing of small pistol versus small rifle primers in a only somewhat related thread. The thread asked about the difference and I posted a bunch of data that I had collected.
IIRC, small rifle primers were around 50 FPS faster and had about 1/2 the extreme spread of pistol primers, but never had any problems with pistol primers.
RIA is crap as far as CS goes.
I also cast up 500 little boolits over the weekend to work up some more loads. Gotta coat them, and then I'll be in business.