I also took a case that was fired in my 30-06, and tried to chamber it. It didn't chamber at all. Ran it through the die with the expander ball removed and chambered again. Again it chambered with zero resistance. So it seems like at this point we can firmly rule out a headspace problem? I will try lubing the inside case neck with some rcbs lube I still have left, and see what happens when I neck it up again.

......the occasional hunter wielding a hopelessly inaccurate rifle, living by the fantastical rule that this cartridge can deliver the goods, regardless of shot placement or rifle accuracy. The correct term for this is minute of ego.