The lead free primers that I recall, created excess pressure. So a small primer was used to reduce the surface area pushed on by the pressure in order to keep the primer from being blown from the case. I do not recall any increase in flash hole size as a result of weak primers--although, there certainly may have been.
Incidentally, are the primer holes in question associated with aluminum cases?
Incidentally, are the primer holes in question associated with aluminum cases?
