I've got a m&p9c and it shoots very well. I really like this pistol but don't recall any problems with ejection. Most of my shooting has been with my reloads, i.e., either 125 grain lead round nose with 5.0 grains of W231 or 115 grain JHP with 5.0 grains of the same powder.
Perhaps these loads are hot enough? Load data gives ~1100 fps with the former and ~1170 with the latter. I'm not sure what the Federal load you are shooting is at.
Thanks, that might really give me a good idea! I'll look up the load data for that and then compare it to what you're saying. Wish I'd gotten into reloading before this madness.