case neck spring back

C

captbill

Guest
I have been working some 30br brass. I have 2 small lots of new Lapua 6br brass,I have kept seperate but put through the same process with the same equipement. One lot the necks came back to .328(96 pices after cull) and the other .325(47 pieces after cull). The lots are very consistant within them themselves. They have been fireformed, annealed and resized with a .323 bushing. Thank God I didn't mix them up.
 
captbill said:
I have been working some 30br brass. I have 2 small lots of new Lapua 6br brass,I have kept seperate but put through the same process with the same equipement. One lot the necks came back to .328(96 pices after cull) and the other .325(47 pieces after cull). The lots are very consistant within them themselves. They have been fireformed, annealed and resized with a .323 bushing. Thank God I didn't mix them up.
Click to expand...

Another reason for neck turning!...............Don
 
springback

All necks turned to 0.010. Thats has nothing to do with it.
 
case nech springback

Perhaps it is anealing but if so why is the affect uniform among those cases from one lot? There is literally less than .001 differance between the cases of the same lot.
 
I've noticed the same thing with varioius brass, domestic along with Lapua and Norma. None were annealed after they left the factory, and all kept in separate lots. The only thing I can imagine that might cause this is slight differences in alloys from lot to lot. I'm sure not a metallurgist, but assuming that the cases in the same lot have all been annealed the same way and made with the same sheet of brass I can't imagine anything else.

Let me say in my defense when the AA guns come out to shoot this down, that my imagination ain't what it used to be. :(
 
Lately, the factory anneal varies quite a bit from lot to lot. When used out of the box as 6BR's, it's not that noticeable. Expanding them to .30 simply makes the differences more apparent. The neck/shoulder area work hardens dramatically when expanded this far.
 
interesting rsults

I had some time yesyerday and thought since I had something odd with my brass I would just start over. I disassembled my sizing dies and soaked all the parts in Carbon killer, tumbled the 2 lots of brass again and resized everything one more time with the same bushing. Now everything is + or - .001" on the neck.
 
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