[JRandomFreeper]

so firing a .380 in a 9mmP chamber could cause a case rupture and damage to the gun and your hand.

You quote from the range officer that chewed me out. I did luck out. I always check ammo now. Always.

/john

[Vinnie_Vidi_Vici]

so firing a .380 in a 9mmP chamber could cause a case rupture and damage to the gun and your hand.

Most likely a .380 in a 9mm chamber would not fire at all. Most autoloader cartridges are rimless and headspace on the shoulder, in this case the leading edge of the case, so there would be too much slop in the fit for the firing pin to hit the primer unless you pointed it straight up! Even then a case rupture shouldn't harm a pistol built to withstand 50% greater chamber pressure but still not a good Idea.

I used to reload 9mm for my Browning Hi-Power using 80 gr. .380 bullets loaded to 1400 fps, it was quite spectacular.