Can you shoot a 380 in a 9mm?

Answer 1

.380 ACP is the same as the 9x17, which is also known as the 9mm Short or 9mm Kurz. It can only be fired in weapons chambered for this cartridge, and is not compatible with the longer 9x19 (9mm Parabellum, 9mm Luger) cartridge, or any other 9mm cartridge.

Answer 2

The only type of firearm that I'm aware of which could safely fire both would be one that does not headspace off of the case mouth (the intended method for both cartridges). This would likely be a revolver with a special clip (sometimes called a moon clip), which holds the cartridge by the groove in it's head. Don't try such a thing with any autoloader. Even when it works, it causes extreme wear on the extractor, as well as variations in accuracy/velocity, and not not be powerful enough to cycle. This information also applies to .40S&W/10mm.