I to have switched to a U die, prior to the U die I was getting bullet setback with R-P 40 brass, now I no longer use R-P brass with 40sw , I still prefer the U die to help ensure I do not have setback issues again.
I would advise that after you have your die's set and achieve 100% pass with plunk and function also make sure that you can not push the bullet in the case deeper with your thumb,