.40 cal can be a bit finicky (at least an EMP 40) if the case size is too out of tolerance. I always trim new casings as they always seem to manufacturer them a bit too long.
For new brass, are you annealing before first use, or can that be done any time?
Just curious as I've never done that or even knew you really needed to.
I'm still a little green on the 40 (I spent a lot of time making fun of it:uhoh
I anneal somewhere around the 7th or 8th firing. It depends on the brass. Some is a lot softer than other.