Maybe you're not belling the case mouth quite enough. Are you also trying to crimp at the same time you're seating? Try backing off your seating die quite a bit then just screw it in a quarter of a turn at a time. Cast or jacketed bullets? Measure the diameter of your bullets if none of the above helps.
BTW, a loaded round is also called a cartridge not a bullet. The crumpled brass is probably not worth trying to re-size.
Report back what you find. BTW, you can pull the bullets and re-use them and the powder.
Regards and good luck for you.