Can you shoot .380 ACP in a 9mm pistol?
No. Same .355-inch bullet, different cartridge — the .380 case is shorter and narrower at the base, so it does not headspace in a 9mm chamber.
The shared bullet diameter is what makes this look plausible and it is the only thing the two have in common. .380 ACP is also called 9x17mm, and 9mm Luger is 9x19mm — the case is two millimetres shorter and, more importantly, narrower at the base.
| Bullet diameter | 0.355 in — the same for both |
|---|---|
| Case length | .380 ACP 17.3 mm, 9mm Luger 19.15 mm |
| Base diameter | .380 ACP 9.5 mm, 9mm Luger 9.93 mm |
| Maximum pressure | .380 ACP 21,500 psi, 9mm Luger considerably higher |
A 9mm chamber headspaces on the case mouth. The .380 case is too short to reach it, so the round has nothing to stop against and sits too far forward. Being undersized at the base as well, it is not held centrally either. This is a feeding and headspacing failure rather than a pressure one — but it is a failure.
Caution: The names are the trap. "9mm Short", "9mm Kurz" and "9mm Corto" are all .380 ACP, and all of them contain "9mm". Read the full designation on the box rather than the first number.
Sources
- .380 ACP — dimensions, pressure, and its 9x17mm and 9mm Short names
- 9x19mm Parabellum — case length and base diameter for comparison
Last checked 2026-09-03. Specifications change between production runs — verify anything safety-critical against your own firearm and the manufacturer before acting on it.
More on ammunition and chambering
- Will a 300 Blackout round chamber in a 5.56 barrel?Yes, and that is the danger. It chambers and the bolt closes, but firing it can destroy the rifle. Never mix the two on the bench.
- Can you shoot 5.56 in a .223 chamber?Not safely. The .223 chamber has a shorter throat, so 5.56 pressure climbs past what the rifle was proved for. The reverse direction is fine.
- Can you shoot .38 Special in a .357 Magnum revolver?Yes. Both fire the same .357-inch bullet, and the shorter .38 case chambers safely in the longer .357 chamber. The reverse will not, by design.
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