Shooting a 380 cartridge in a 9mm pistol

[GAGunguy]

What do you guys think about shooting the proper ammunition in the proper guns? I know Guys that have been doing it for years and never an issue. Thoughts?

I put a 556 in an AK mag chambered for 7.62 (on accident)! Guess what? It fired and the case ruptured and got stuck in the chamber. Not a great idea.

 

[ReservoirDawg10]

I never imagined that a question about shooting a 9mm short in a 9mm pistol would cause so many people to hyperventilate.

To those of you who peed their pants, please accept my most sincere apology.
Now, get out of the fetal position, off the floor, and try to get a handle on your nervous shakes.
It will all be alright.

I didn't realize that shooting a 9mm short in a pistol designed for a 9mm was suicidal - a cartridge with the same size projectile with maximum pressures that is about 50% of the pressure of the cartridge being replaced not to mention many of the pistols being designed for +P and +P+ ammo and huge design safety margins on top of that.

Curious as to the "why."