One thought; are you "drilling out" the crimp or beveling the primer pocket mouth? "Drilling out" by trying to drill with the drill bit the same diameter as the pocket or using a drill larger than the pocket to just bevel/chamfer the pocket mouth?

When I have nothing else to do I occasionally sort my 9mm brass by headstamp (I know it doesn't really matter, but I find some weird/odd headstamps and I'm playing with my "reloading stuff"). I have a 1/2 gallon jar of military headstamp 9mm cases of a few different manufacturers, but I have never had a problem with removing any primer pocket crimps with a plain old 60 degree countersink...