I never pushed the shoulder back more than .002 from a fired round. Except the first piece i ever sized. Should have been when i figured out it was the wrong die.Let's think about this for a minute. How much were you pushing the shoulder back? If you were running the die jammed down on the shell holder, you were pushing the shoulder back about .080" too much?
If that is the case, I'd think you should throw the brass away that has been sized in that die. Nothing good comes from excessive stretching at the head-body junction.