I have shot a few 380s out of a 9mm by accident. The bullets are a bit smaller and do not build pressure. They sound more like a pellet gun than a 380. I have been on another site and some are trying to say it can not be done with out blowing up your breach. LOL Not true at all. The brass will crack or at least expand a bit over normal, but it will not blow up the breach. I do not recommend trying it on purpose. I also knew a few guys up north who would shoot 380s out of 9mm maks, its the same type of thing the bullet is a bit smaller in diameter and rattles down the barrel. I don't recommend doing it but it can be done without damage. There was even a video of a guy shooting 9mm or 9x19 out of a 9mm mak, It worked but I would not do it, that may cause a problem, the 9mm parabellum may be higher in pressure.

9x19 in a 9x18 PA-63 - YouTube