I don't use expander/decapping rod anymore on fired cases. Universal decapper(.22 and larger). Then the fl sizing die, the sizing die setup using comparator measurements(or the stripped bolt method). I use a mandrel die to get the inside of the case neck to 0.002-0.003(bolt gun) smaller than bullet bearing surface diameter. No crimping, even AR ammo, so my seating die is set 1 turn BACKED OFF the case mouth(unless die manufacturer instructions different). 17 and 20 cal I have turned the expander down so there is no contact inside necks, only decapping. I haven't had any "donuts" and I don't turn necks, even with a couple rifles having custom minimum saami chambers. Many years ago I experienced the same situation with the 7saum, setting the sizing die, inside neck diameter and no crimping eliminates that slight shoulder expansion that causes bolt closing issues. New brass I just use the mandrel die to make inside neck round and correct for bullet tension, since most new brass is short of headspace.
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