I know the problem is from not having the bullet aligned properly, thicker brass adds to the problem , I get the bullets straight but I'm sure not perfect , in most cases the die aligns but I guess with the combination of thick brass and a bullet that isn't exactly in line . Hornady has a sleeved seating die to help align the bullet . I'm going to give it a try . 45ACP is a easy round to reload , the cases never seem to reach trim length , 230 FMJ RN less problems with feeding , pretty simple , just want them perfect.
If the bullet is setting catywompus it will really flare out mouth as it destroys case and bullet. Been there done that!
I read a artical on the 45 acp. The case actually shrinks over the course of repeated firings. Test was done starting with new unfired starline brass. The results were amazing.
I use the hornady's with tape crimp and like them alot.
Here's some things I learned.
To much crimp will bulge case at the mouth.
If cases " are not the SAME LENGTH" you will not get a consistent crimp. Some will have more some less. If to short maybe none at all.
If cases are to long for die setting you will damage case resulting in crushing and or bulging.
I figured all this out the hard way after purchasing my Dillon last year.
As stated brass was mixed, I'd bet different lengths. I'd also venture to say rounds with bulges are longer than the case used to set up die. Might even have same head stamp.
IMHO, you got a couple choices.
Trim all cases to same length, or length sort and set die to the longer cases.
Yeah some will have propper crimp whereas others wont.
Sort your head stamps" I do"
Seat in 1 step, crimp in another.
" Separate operations "
No crimp at all
" personally I wouldn't not crimp"
I'm by no means an expert as I just set my Dillon up last year at this time.
Produced around 3000 rounds of 45 and 380 ammo in process.