To illustrate the problem I've just photographed the difference in primer seating.
Same batch of primers, I find about 2/3rds are OK and the other 1/3rd sit just proud. All were Remington 209's.

"fat" rim primer sitting proud : http://i633.photobucket.com/albums/u...ps77bbb929.jpg

"thin" primer sitting flush : http://i633.photobucket.com/albums/u...ps0c49d4bc.jpg

Yes, that's enough to make the cylinder bind. The "fat" primers work great in my Remington 1858 nitro conversion though so they still get used.