I have been reloading about16 years or so and have loaded thousands of rounds, never had a primer pop until about 2 months ago. I typically load on my Dillon 550B and never have had any issues. I picked up a Lee Pro Master a few years back to load 9s and 40s for volume. It does load faster but the priming system is finicky. Not real sure what happens, but sometimes the primers get out of sync for lack of a better term and you end up crushing a primer. Had one pop and it did make me flinch. Now when seating the primers, my butt cheeks tighten up when using that press.
Problem with it is, the primer seating is on the same stroke as the sizing. So you don't know if the primer is why it is harder to pull or if the brass is just harder to size, so you sometimes go ahead with the stroke, that is why it popped. On my Dillon the seating process is all by itself, if it doesn't feel right, you know it is a primer issue.
Things like this is why I ALWAYS wear safety glasses when handling powder, primers and loading cartridges.
Rosewood
Problem with it is, the primer seating is on the same stroke as the sizing. So you don't know if the primer is why it is harder to pull or if the brass is just harder to size, so you sometimes go ahead with the stroke, that is why it popped. On my Dillon the seating process is all by itself, if it doesn't feel right, you know it is a primer issue.
Things like this is why I ALWAYS wear safety glasses when handling powder, primers and loading cartridges.
Rosewood