Would have to agree with Jon on this... Couple questions , How accurate are your scales and secondly do you have a means to measure unfired cases along with fired cases.

The load you mentioned by most accounts should be very mild even if the throat was so short that you were jamming bullets.

Quite frankly it doesn't sound like you can even safely fireform brass so as to properly measure the brass after firing and then properly set up the die.

I would get my hands on a no go gauge and see if it will pass that test , if it does then perhaps your sized brass is terribly oversized with regards to bumping the shoulder back too far.