223 brass shrinking?

M855

Sergeant
Full Member
Minuteman
Nov 29, 2009
399
1
53
East TN
Brass has 5 loading on it mixed dates of LC fired in the same Rem 700,trimed to 1.750 now all 50 rounds are 1.743-1.748 ,What gives shouldnt it grow instead of shrink,is it time to throw away this batch of brass
 
Re: 223 brass shrinking?

Are you sure about the trim dimension? What did you use to trim with? Did you measure after trimming? Most of the times I have seen cases shrink is the first time firing to fire form new brass to a specific chamber.
 
Re: 223 brass shrinking?

Yes im sure,used a L.E. Wilson trimmer,checked after trimming, this is the first time Ive seen the brass shrink it always grows a little after firing,used the same powder charge,primer and bullet the only thing that was different was the outside temp was in the low 40s
 
Re: 223 brass shrinking?

M855,

My Lapua .223 and .243 quit growing after 5-10 firings, but this was in fairly tight chambered rifles. Even after annealing, they didn't grow any more. I cannot give a reason, just letting you know what happened.

HTH,
DocB