Well, I have about the same issue. I keep my SD ammo loaded in my mags and occasionally let the springs reset. I did buy 4 32rd 9mm mags to go with my 9mm conversion for the range. The 32rd mags come in handy if you just want to keep them loaded before taking them to the range. Anyway, 9mm and 40 use the same factory mags and work fine. The 32rd (20 in 40cal) start flipping the 9mm bullets up in the chamber and jam the 40s between the slide and feed ramp. I can recover quickly, but I should never have to. I can't tell you any more than that.