If you are trying to prime some range brass you might have some "military" brass that has a crimp to hold the primer secure.
I ran into that tas well. I bought an RCBS primer swag kit and run all my range brass through it. You also might try Winchester primers. That worked the best for me. Someone on here recommended it to me.
I still get an occasional primer that flattens or peels back but free range brass is worth the extra effort.
Hope this helps.
