[cwo4uscgret]

Kilibreaux - a .380 can be fired out of a 9mm AR; but shouldn't be done. Some .38 Special revolver cylinders are just long enough that you could, but shouldn't shoot .357 Magnum out of them with more then likely disasterous results.

I've done the .380 out of a 9mm AR one round. As soon as it went bang I knew it. I was lucky - the empty casing was extracted and ejected but I knew something was different - the bore was clear. No apparent damage so I after I removed the unfired rounds from the magazine and didn't find any other .380 rounds, I went back to shooting.

Although it has been working for you I think you've been real lucky; other people who have shot the "wrong" ammo out of their guns haven't been so lucky. The following rounds are very similar in size, by a few milimeters but could be disasterous if shot out of the wrong gun: .38 acp; 9mm, 8mm Largo, .380 acp, .38 Super. Almost all .38 Super ammo is marked +P; to warn those who have pistols chambered in .38 Auto not to use the Super round in their guns. The rounds are almost identical - until you look at the ballistics and see that .38 acp is a very mild loaded round when compared to .38 Super. Many beautiful older .38 acp pistols have been destroyed, often causing injuries to the shooter when the gun blows up.

Although you can shoot 9mm in your .38 Super you shouldn't. There is some 9mm ammo, made by Hirtenberger, that both the manufacturer and BATFE jointly wrote a letter advising everyone to not shoot that ammo out of any pistol - it was designed and loaded for sub-machine guns being used in Arctic conditions...it is like +P++++ hot.