Firing 380 Auto in a 9mm Luger?

KentM · March 28, 2023, 12:44 PM

I reload 9mm from range brass, and sometimes I find 380 Auto casings. So far I've always caught and eliminated them but I'm always afraid of one slipping through.

So what would happen if I accidentally loaded and fired a 380 (with a 9mm powder load) in my 9mm semi-automatic?

lugerstew · March 28, 2023, 12:51 PM

I think loading a 9mm powder charge in a .380 case would be dangerous, I have seen a video though, of shooting factory .380 in 9mm pistol and if I remember nothing serious happened, just search for myth busters firing .380 in 9mm.

**44 AMP** · March 28, 2023, 02:15 PM

Quote:

So what would happen if I accidentally loaded and fired a 380 (with a 9mm powder load) in my 9mm semi-automatic?

Nothing good!

IF it even fits, 9mm powder loads are about 25% more than .380, and combined with the difference in case volume, significantly higher than normal pressure should be expected. I don't know how much, but it could easily be into the range that would damage your gun, and possibly you!

Proper inspection of your brass before, during, and after the loading process will prevent that.

If you are running a progressive press (and particularly with a case feeder) inspection of each piece of brass before loading the hopper is important.

Additionally, progressives don't have the same "feel" feedback as single stage presses. The .380 and the 9mm use different shellholders, so a .380 case probably won't be held properly.

The .380s specs smaller than the 9mm, so its going to feel unusaully "easy" going into the sizer die. The shorter case isn't going to work a powder through expander die the same way, likely resulting in less case mouth flare, and possibly an incomplete powder dump.

The .380 run though 9mm die settings might not be flared enough to easily seat a bullet, and of course, if it does, its not going to be seated to the correct depth in the shorter case.

All these things should be either tactilely, or visually evident, but a progressive press can make them difficult to feel or see, unless you are specifically looking. If you do manage to miss them and load a .380 case with your 9mm setup, the resulting round should be very obvious compared to the other rounds loaded.

You are the only QA/QC that your reloads get. Sorting and checking range brass is an important step to prevent problems later in the loading cycle.

Generally speaking, when a .380 fires in a 9mm gun, its being held in place by the extractor. This usually doesn't damage the gun but may or may not cycle the action, depending on the gun.

Overcharging a .380 case with a 9mm powder charge would be a BAD THING.

Keep a close eye on what you're doing, and be safe!

ghbucky · March 28, 2023, 02:37 PM

delete

jetinteriorguy · March 29, 2023, 05:22 AM

I forget where I purchased it, but many years ago I bought a filter that will retain 9mm while allowing.380 brass to fall through the slots milled into it. This disc fits right in a bucket I happened to have, it was a two gallon bucket I believe. Just throw a handful of brass on top and shake it around until all the cases have either fallen through or are sitting in the slots. Works great and easy to use.

**Unclenick** · March 29, 2023, 11:37 AM

Short of special equipment, the easiest thing to do is just to stand all your cases up on a flat surface and visually scan for the shorter cases. It will be obvious.

The narrower outside dimensions and straight walls of the 380 case mean that with a bullet seated to the same COL, the 9 mm case has about 0.46 grains more water capacity. The 380 case has thinner walls, so the concern is that a 9mm Luger load would swell the brass out past the narrower rim diameter of the 380 cases in the wider luger chamber and pierce that thinner brass, blowing gas out of the gun breech. With a mild load, it may simply expand and deform the case without letting go, but it doesn't seem like a good plan to count on that.

Marco Califo · March 29, 2023, 12:00 PM

Quote:

a filter that will retain 9mm while allowing.380 brass to fall through the slots milled into it. This disc fits right in a bucket

https://www.midwayusa.com/product/1012981254?pid=270949

jetinteriorguy · March 30, 2023, 05:51 AM

Quote:

Originally Posted by Marco Califo

https://www.midwayusa.com/product/1012981254?pid=270949

That’s the one.

reddog81 · March 30, 2023, 10:09 AM

The results will depend on the load you are using. Seating to 9mm OAL will somewhat mitigate using more powder and a bigger bullet. Most 9mm starting loads are in the 25,000 PSI range. However variation in case capacity will effect the pressure also.

I've tried it using a starting charge and 115 grain bullet after a shorter .380 case made it through the reloading process on me. No noticeable difference was detected upon firing. Using a moderate load and a 124 grain bullet resulted in noticeably more flattened primer than the 9mm brass. I wouldn't recommend doing it and going to the more extreme end of the spectrum like +P loads might be more interesting. Given that 9mm brass is more prevalent there is no good reason to do this...

March 28, 2023, 12:44 PM	#1
KentM Member Join Date: January 4, 2021 Posts: 19	Firing 380 Auto in a 9mm Luger? I reload 9mm from range brass, and sometimes I find 380 Auto casings. So far I've always caught and eliminated them but I'm always afraid of one slipping through. So what would happen if I accidentally loaded and fired a 380 (with a 9mm powder load) in my 9mm semi-automatic?

March 28, 2023, 02:37 PM	#4
ghbucky Senior Member Join Date: June 12, 2020 Posts: 1,177	reloading 30 carbine delete

March 29, 2023, 11:37 AM	#6
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,063	Short of special equipment, the easiest thing to do is just to stand all your cases up on a flat surface and visually scan for the shorter cases. It will be obvious. The narrower outside dimensions and straight walls of the 380 case mean that with a bullet seated to the same COL, the 9 mm case has about 0.46 grains more water capacity. The 380 case has thinner walls, so the concern is that a 9mm Luger load would swell the brass out past the narrower rim diameter of the 380 cases in the wider luger chamber and pierce that thinner brass, blowing gas out of the gun breech. With a mild load, it may simply expand and deform the case without letting go, but it doesn't seem like a good plan to count on that. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

March 28, 2023, 12:51 PM	#2
lugerstew Senior Member Join Date: September 22, 2019 Location: Colorado Posts: 260	I think loading a 9mm powder charge in a .380 case would be dangerous, I have seen a video though, of shooting factory .380 in 9mm pistol and if I remember nothing serious happened, just search for myth busters firing .380 in 9mm.

March 29, 2023, 05:22 AM	#5
jetinteriorguy Senior Member Join Date: April 28, 2013 Posts: 3,182	I forget where I purchased it, but many years ago I bought a filter that will retain 9mm while allowing.380 brass to fall through the slots milled into it. This disc fits right in a bucket I happened to have, it was a two gallon bucket I believe. Just throw a handful of brass on top and shake it around until all the cases have either fallen through or are sitting in the slots. Works great and easy to use.

March 30, 2023, 10:09 AM	#9
reddog81 Senior Member Join Date: October 16, 2014 Location: Iowa Posts: 1,635	The results will depend on the load you are using. Seating to 9mm OAL will somewhat mitigate using more powder and a bigger bullet. Most 9mm starting loads are in the 25,000 PSI range. However variation in case capacity will effect the pressure also. I've tried it using a starting charge and 115 grain bullet after a shorter .380 case made it through the reloading process on me. No noticeable difference was detected upon firing. Using a moderate load and a 124 grain bullet resulted in noticeably more flattened primer than the 9mm brass. I wouldn't recommend doing it and going to the more extreme end of the spectrum like +P loads might be more interesting. Given that 9mm brass is more prevalent there is no good reason to do this...