I had a weird thing happen to me today while reloading. I am reloading .357 for the first time in 25+ years. I got some once fired brass from different manufacturers recently.  I separated them apart by manufacturer. I started running the PMC through my sizing/decapping die and the primer would not drop out of the case. Now, before you recommend I don't have the die and/or decapping pin down far enough, it is. Everything is correctly configured. What I believe was happening is that the primer was getting stuck on the end of the decapping pin with so much force that when I brought the case back down the primer actually went back slightly into the primer pocket. I could remove the case only after wiggling it around to get the primer to drop. Or by doing a second stroke on the press. The rest of the brass from other manufacturers dropped on the first stroke as is supposed to happen.

Has this happened to anyone else? Any suggestions as to how to keep this from happening again as I have 100 or so more PMC cases to resize/decap?

Same thing happens to me with RWS cases.  Out of 100, I'll only be able to decap at best 10.  I always forget to check if by some chance those 10 were reloads, and the other 90 were once fired factory cases.  Sorry, no real solutions to offer, as I just sort them and throw the RWS out.  I'd rather toss them than deal with the interruptions when I'm reloading.  This is for 9mm and 45 ACP on a 550B.

Sorry, haven't heard of this happening.  Only time I've had issues with primers is when they've been crimped.

These are once fired PMC cases. I noticed that the primer is very soft in these PMC cases after inspecting some of the primers that came out of them. Also, the little metal piece inside the primer is deformed and in some cases fell out after the primer came out. This is not the case for all the other cases including all the .223 and 9mm I have reloaded. Interesting to note that the primer pockets of the PMC cases were very clean upon inspection. Some to the point that I felt they didn't need cleaning before reloading them.