I'm not sure I understand how (over)crimping can lead to setback .... could you elaborate?
Alright. Take a barrel out of one of your pistols and look down the barrel from the chamber side. You will see that the chamber is slightly wider than the barrel and that there is a ridge in the barrel. That is what your case indexes on (stops the forward movement of the case). If you apply to much crimp on the case, it does not stop where it should and is pushed into this ridge. This compresses the bullet in the case and does not allow for it to release from the case and go forward. It is jammed into the case, and hence into the barrel. When you fire that round, the bullet will be jammed and all the pressure has to go somewhere. Where? Back to your slide, mag well and frame. The gun might very well grenade in your hand.
Do not crimp pistol cartridges, only remove the flair.