In my old age it was pointed out to me that most cases stretch a bit on first firing, some brands more than others. Tried this https://creativereloadingsolutions.com/product/the-perfect-crimp-hull-trimmer/ and got every single hull to star crimp perfectly. Even what I consider some junk brand hulls loaded, crimped and fired fine when matching the correct wad to a given hull. Hulls only stretch on the first firing so only need to trim once during its lifetime. Used a Lee LoadAll and a Mec600.It's been over 30 years for me. Components may have changed.
I found Winchester AA Trap to be the best quality hull. The others tended to bulge and not crimp properly. I second the advice to be ready for powder and shot spills. I used a coupe different MEC loaders. Quit because it was cheaper to buy the dove loads plus I never could make high brass pheasant or other large game loads work well.