TexasCHLforum.com

I had the same problem with the PPU brass when using RCBS dies and 9mm. What was happening in my case was that the primers are so tight in the case that the primer was pushing out but it was getting stuck on the de-priming pin and pulling back into the case. So when I tried to seat the new primer it pushed the old primer completly back into the case. I removed the pin and rounded off the tip a little. The RCBS pin is a little bigger at the tip. I just took a file and took the mushroom off. No problems now. Previously I had tried extending the pin as well.
I use Dillon dies for .45. With the spring loaded die, I've had no trouble at all with the ppu brass.

Try sorting some PPU brass and after de-priming find a way to look at the depriming pin before or while coming back up with the handle and you'll see if that is the problem.

Thanks,
Eric