A much more significant area of concern:
In my opinion, all of the seating dies I am aware of, currently available to the general public are all inadequate for seating bullets properly. A much more critical measurement to make on a loaded round is the measuremt of the OAL, measured from the base of the case to the spot on the bullet that will engage the lands. This measurement, unless one is jamming hard, is what determines the accuracy of loaded rounds. As I was recently told by a well known die maker who agreed with my assessment, they are aware of the situation but it would take a major change in design to fix the situation, which I took to mean they were not going to fix the situation. I guess most peole are satisfied with "Close Enough".
I won't re-visit the causation of the problem but if one could load bullets without ever having to be concerned rather or not they came from the same machine or bullet making session then one would never need to be as concerned about having correct OALs. A proper die would always leave the bullet positioned where it needs to be.
A friend has come up with a die setup that uses bushings instead of a stem for seating bullets. This, to me, makes the most sense in designing a die that will assuer consistent OALs.
Another friend the other day, in conversation, used the expression " Picking out Fly S---". Agreed I think, however, both he and I agree it is worth doing when loading match grade ammo.