Thread: Weird shoulder bump...

@Edunn when you set up your die did you use the same piece of brass each time you screwed the die further into the press?
I have read that that each time you screw the die in you should use a different piece of brass. If the same piece is used it work hardens and springs back more which gives the illusion that you have a .002" shoulder bump. The next piece of brass will spring back less because it has only been sized once. When you measured the second piece it may well have bumped back .005".

Yeah I set my shoulder bump by progressively adjusting the die after sizing and measuring different individual pieces of brass - only sizing each once. This means the first few until the die is set properly have a slightly different bump, but I don't really care.

Originally Posted by Tech

@Edunn when you set up your die did you use the same piece of brass each time you screwed the die further into the press?
I have read that that each time you screw the die in you should use a different piece of brass. If the same piece is used it work hardens and springs back more which gives the illusion that you have a .002" shoulder bump. The next piece of brass will spring back less because it has only been sized once. When you measured the second piece it may well have bumped back .005".

Crap - this is exactly my mistake. Thanks mate, this will be why I'm seeing the issue. Unfortunately I set my die and sized the next 50 pieces so they were all consistent but will know for the next firing, thankyou!