Just reading the thread again. I noticed that you mention .0025 runout on once fired, unsized cases? Am I reading this correct?
If that's the case (no pun intended) then the chamber isn't very concentric IMO. I find very little runout on necks of fired cases.
The old saying is "Out 2 on fireing = Out 4 on sizing = Out 8 on seating".
In other words, each step usually doubles runout. I have found this to be more or less true on more than one rifle/die.
A good chamber should have < .001 total run out on fired cases, measured on the necks (and assuming the necks are concentric and not dented/deformed(uniform thickness, not ejected hard)).
But anyway, after reading your post again; I am assuming you already knew some of this.
sure as a politicians promise it went south.....006 runout.
Let me know on the expander ball?