There was a thread a few weeks back that mentioned the possibility of loading 9mm into .40/.357 magazines, specifically that a S&W rep did this to demonstrate reliability.
Anyway, I just got some of the 10-round .40/.357 magazines, and while they hold 12 rounds of 9mm, the span of the magazine lips won't hold 9mm cartridges reliably. They pop out far too easily, at least for my comfort. While this trick may be fine for demonstrations, I woud not do this on a regular basis.
Interestingly, the "load 9mm into .40 Auto magazines" trick works well for 10-round HK USP40 Compact magazines, and hold 13 rounds.
Anyway, I just got some of the 10-round .40/.357 magazines, and while they hold 12 rounds of 9mm, the span of the magazine lips won't hold 9mm cartridges reliably. They pop out far too easily, at least for my comfort. While this trick may be fine for demonstrations, I woud not do this on a regular basis.
Interestingly, the "load 9mm into .40 Auto magazines" trick works well for 10-round HK USP40 Compact magazines, and hold 13 rounds.