A few days ago I picked up a bag of new Federal American Eagle 7.62x51 NATO brass. As part of the first time prep I ran the necks over an expanding mandrel (Lyman M-die) to round them out and make the hole size uniform. I then assembled fifty of them into an approximation of Lake City M852 match ammunition.
Of the fifty there were fourteen cartridges showing .005" or more runout on the bullet ogives as measured with my old Sinclair test fixture. The numbers were written on the case bodies.
After firing they were deprimed and lightly neck sized with a Lee collet die. They were then FL sized using a Forster die with a custom honed neck and no expander in place, trimmed, and finally expanded with the M-die to match the first loading.
The following pairs of numbers indicate the first and second loading runout of the cartridges:
8,1
7,2
7,1.5
6,1
6,1
6,1
6,1
6,1
6,2
5,2
5,1
5,1
5,1
5,3
At this point I have not measured the case neck walls for uniform thickness. Experience tells me if I do take that measurement the one that only improved from .005" to .003" will not be the one with the best neck.
I've opined before that 1x fired brass is your best bet for tuning loads, and here's some evidence why. Some of you are thinking what's new here, but this note isn't really for the old hands.
