Thread: Brass length trimming question

Originally Posted by robh500

Just found a fired one, measured, sized and measured again, it grew 20 thou!
I might invest in a bushing die.

Thats excessive. New Peterson 280ai I have here is 2.520 . Fired 2.526 Resized with minimal shoulder bump 2.525. What was the length of the fired case before sizing?
Have you checked headspace ( base to shoulder) before and after sizing? to confirm correct sizing die set up? Does the sized case chamber easily or is there some resistance closing the bolt?
I agree with @grandpamac but in this case Peterson brass is a little thicker in the neck than others , its possible that over annealing making the neck and shoulder to soft combined wiith the thicker neck might allow the button to stretch it. Just a slim possibility though. A simple test would be to remove the button with your current set up , size the case and see if it still grows.
I personally wouldn't bother annealing new brass on the first firing. For 95% of shooters the benefits of annealing every time are overstated. Im up to the third firing on this Lot with no drop off in ES or accuracy at all and my 243ai is over 10 with lapua brass. A lot of variables.