I have my doubts as to whether or not trying to stuff a large primer into a small primer pocket would have set off the priming tube supply as Slamfire mentions. First, the primer is picked up at the bottom of the supply tube. On my Dillon 550B, the primer travels a full two inches to the seating station where it is surrounded by the steel cup that picked it up. I can't figure out how detonating a primer during primer seating detonates the primer supply tube, two inches away.
I might add that I've crushed more than my fair share of misaligned primers without once ever have a detonation. I've even decapped live primers, distorting them a bit but without a kaboom. Primers apparently also need percussion to set them off. To detonate a primer during priming indicates that somebody was working way to fast and not by feel.
As I uniform my primer pockets, range pick-up brass with small pockets are found before reloading and set aside until the batch is large enough to warrant changing over the primer feed on my Dillon.
Int'l Assoc. of Law Enforcement Firearms Instructors