Can you shoot a 380 acp from a 9mm?

Answer 1

No, you cannot. Firing ammunition other than what the firearm is chambered for is dangerous, and has the potential to result in injury or death.

----

A 9mm revolver that uses moon clips to hold the rounds is capable of firing .380 ammunition as well. Such a revolver headspaces the cartridges from the moon clip.

Non-moon clip 9mm revolvers cannot fire .380 as they headspace from the case mouth. A .380 round will slip further into the chamber when struck by the hammer and likely result in a failure to fire.