[Dave S]

But you can feed .380 in a 9mm. Bad idea.

What happens? Will it scar the barrel or worse? Curious as I currently have 9mm and I still have a couple boxes of .380 sitting around.

While I asking questions, how do you discard safely ammunition you can not use?

[Double Tap]

The head diameter of the .380 is smaller than the 9mmP, so firing a .380 in a 9mmP chamber could cause a case rupture and damage to the gun and your hand. It is also possible, though remote, that the .380 round could slip out from under the extractor and get pushed up into the chamber. Then if a 9mmP round were chambered behind it and it had a FMJ bullet it could conceivably set off the .380 round with the slide out of battery. This would also cause gun damage and possibly injury.

[JRandomFreeper]

Will it scar the barrel or worse?

My single screw-up experience was fairly tame. The round felt wrong and didn't eject. When I dropped the mag and tried to clear the case (barrel pointed down-range), I found the case lodged in the barrel. We (range officer and I, after my @$$ chewing by said RO) used a cleaning rod to back the case out and the pistol fired normally on the correct ammo.

/john

[RANGERAIRBORNE]

Since the .380 cartridge is shorter and smaller in some dimensions than the 9mm, it may very well rupture when fired due to lack of support (not fitting snuly into the chamber is a bad thing). This will certainly tie up your gun, and may well damage the chamber, the extractor, and various important pieces and parts.

This problem arises every deer-hunting season, when folks who shhot oinly once a year get confused and load their rifles with the wrong ammunition (say, .280 Remington in a 30-06). You should make it a habit to carry ONLY the correct ammunition for the firearm you are currently using.

Your question about how to dispose of unwanted ammunition is really an excellent one- NEVER discard it in the trash, or into a dumpster or landfill. I recommend taking it to your friendly local gunstore , and asking the proprietor to dispose of it for you (or sell it, whichever comes first!) Do not attempt to remove the bullets from the cartidges using household tools in order to render the ammunition "safe"- this will almost guarantee a bad accident- and I have seen a few of those. By the same token, burning it is extremely hazardous to everyone in the vicinity.

[sniklacg]

In a rimless cartridge like the 380 ACP and the 9MM Luger the depth that the cartridge seats (also known as head space) into the chamber is set by the front rim of the cartridge. In a many rimmed cartridges like the 38 Special and 357 Magnum the head space is set by the base rim. That being the case, you can safely fire a 38 special in a 357 magnum because the case is shorter and is head spaced on the base. A 357 cartridge will not drop far enough into a 38 special because chamber isn’t deep enough to allow the longer case to fit. This was by design to keep the heavier loaded 357’s from firing in lighter framed guns.

If you were to drop a 9mm cartridge into a 380 Auto, the case would bottom out in the chamber and leave about a quarter inch sticking out of the chamber and the action would not close. On most guns if you were to drop a 380 Auto cartridge into a 9mm the case would drop too far into the chamber and the firing pin would not reach the primer. If by chance you could get either to fire you would likely have problems because of either an action that was not closed or too much movement of the case inside the chamber.

In both cases, as someone above mentioned, caliber sizes are mostly naming conventions. 38 Special and 357 mag both use a .357 caliber bullet. 380 ACP and 9MM both use a .355 caliber bullet.

It’s even more interesting to look at rifles. There are bunches of 30 caliber rifles that all shoot varying shapes and weights of bullets that are all .308