I noticed a little while back that I am getting some discrepancies in my OAL (measured at the ogive with a hornady bullet comparitor. Bryan Litz said that he had seen some OAL discrepancies due to excessive neck tension, and I think that is my problem, since I am FL resizing with no expander ball, then chamfering to avoid jacket shaving. My reasoning behind this was to avoid run-out as some people believe that expander balls pull the case neck out of alignment. So my questions is: should I just ignore that and use the expander ball, or should I just go for a mandrel setup? Thanks.
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danblack7.62
Oct 17, 2018
Expander ball or mandrel for neck tension?
Expander ball or mandrel for neck tension?
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What bushing are you running, and whats yoyr neck tension? Is this new quality brass or fired? If fired brass are you annealing?
if you’re not using a bushing die, I recomend it. get rid of the expander ball, use a mandrel. I personally use a bushing slightly smaller, then use a mandrel.
Neck tension is a real bug-a-boo that's kinda hard to diagnose without knowing much about your setup. The neck tension will change based on how hard the brass is based on how many times it's been fired, Generally speaking, the more time it's been fired, the more resistant it will be to changing shape (up until it cracks).
Correct me if I'm wrong, but it sounds like you're running a conventional neck sizing die, if so continue using your expander ball, yes, OAL will change based on brass hardness, as well as the difference in ID/OD of the bullet. (imagine cramming a 8mm bullet into a .308 and then wondering about neck tension). Typically you want your brass ID to be about bore diameter (so .220 for 5.56, .300 for .308 and so on) if the diameters are off more than this, you will end up having problems with the bullet seating off-axis in the case. You may correct this with a mandrel, but I would put the expander-ball as the more successful method of accomplishing this. You could get away from the expander ball entirely by turning the necks of your cases, and then using a properly sized neck-bushing sizer.