What brass is the most recent it has been making this popping with, head stamp & caliber please? I'm asking because it's possible your priming pockets that were crimped or staked, that would deffinitely cause you some popping.
I'll get a couple now and then that will kind of pop when they go in, but only a couple out of several hundred or more. I don't use an RCBS hand priming tool though, I use an RCBS priming die, but priming is priming and the primary elements of the tool are the same, large and small ram tips, large and small shrouds.
What to do. My first thought is you may be using the wrong priming tip, small primer/ large primer. For instance, if you used the large tip for a small primer the primer will slop around in the shroud that surrounds the ram tip, allowing the primer to mis-allign. Or you could have the large shroud and the small ram tip, which is still going to cause a lot of mis-allignment. And the other way around such as using the small shround for large primers will likely prevent the primer from sitting square in the shround, or it could prevent it from completely sitting into the ram tip shround.
Their insn't a bunch of things that can go wrong with a priming tool, so it should be quite easy to identify the culprit. You also might have a very small nick or other defect on the ram tip or the shround that is interfering with the primer squaring up to the pocket.
GS
