interesting observation - neck dia. pulled brass

[JBMauser]

I just don't know what to make of it.  I had a batch of loads I was under whelmed with,  The load - 16gr of 2400.  I pulled about 20 rounds to try some others.  The brass set on my desk for ages.  I pulled it out tonight and thought I would just flare the mouths and stuff them again.  I grabbed my caliper and checked a few necks.  some were as sized and others would barely hold the pill in place.  Same lot of brass.  Variance of 3 thousandths.  Some stretched?? or took a set? Thoughts...JB

[Leftoverdj]

Couple of possibilities come to mind. If you originally loaded with as-cast bullets, you could have gotten that much variation. If that ain't the case, you likely have a hardness problem. Dead soft annealed brass has little or no spring back. Another possibilty is that you are as sloppy as I am and keep the brass segregated by lot but not by times fired. If some of it had been fired more often, it would be harder.

Me, I'd either toss it or anneal it, depending on the cost of the brass.

[JBMauser]

Good points.  The number of cycles should be the same.  They may have been loaded as cast.  I think I will need to preform a controlled experimant at some time.  Thanks,  JB