Good call on the expander ball as a cause. I like that theory. What I mentioned only can only happen by a 1-2 thousanth or so until you can't even chamber the round.
Lots of us don't use an expander ball. I use a Forster full length resizing die with the expander removed. Then run a Lyman M die with some imperial dry neck lube but not all the way to the step. This opens the neck by 1 thousanth.
Another issue with your prepped cases is there is way too much variance in headspace. I measure headspace like you with the Hornady tool and calipers. My brass is very consistent, with headspace variations of 1 thousanth or less.
Try a test, grab 10 unprepped cases. Remove your expander ball and size them then measure them and see if they are consistent...if they are consistent you know the expander ball is causing problems.
Another thing to check is measure the same case 5 times. Do you get the same measurement? If not that is a problem.
Sent from my XT1565 using Tapatalk
Bookmarks