Are you trying to seat and crimp in one step?
When I'm loading steel and crimping with the die, then switch to brass I get this if I don't adjust the die. Steel takes a lot of force, and the hornady dies I have apparently don't taper crimp, instead they seem to roll crimp, so they are very finicky. The FL sizer also sizes the rounds too much, so the front ends rattle in the magazines, and the tips of the bullets sit a bit low. If you run into older hornady x39 dies, pass on them.Are you trying to seat and crimp in one step?