What happens if you accidently load a 380 case with 9mm and try to shoot it?

if you are using the correct shell holder for the 380 a 9mm will not slide in. and if you crimped a 380 case with 9mm dies, you would notice a lot of bullet exposed (assuming the case wasnt crushed guring assembly) and perhaps look closer. bullet wise, the heavier 380's leave off where the lighter 9's start. size wise, .355 for 380 vrs .356 for 9mm, might be a slight pressure problem--less so for lead than jacketed. don't know re 9x18, 9x21 or others.

ahhh.... why are you lubing 9mm cases? not usually necessary for straight cased ammo. (perhaps steel dies?)

i use the same shell holder for 9mm 9mm mak and 40sw- and I'm pretty sure 380 goes in there are well. you just gotta keep an eye. the case capacity is so much smaller in the 380 though that you'll probably get an overflowing case of powder- tipping you off to your error. 9mm mak will feel weird sizing, as the bullets for it are over .360

many 9mm handguns, though call for a .356 dia bullet, actually have bore diameters in the .357-.359 range.

Part of your reloading procedure should be to carefully inspect every case prior to getting to the lubing part.

Things you may find include split necks, rocks & spider nests, and .380's mixed in with your 9mm brass.

I also sort range pick-up by brand, as there is a very wide variation in 9mm brass that can effect crimp, or even pressure. And some of it may even have crimped primers.

Shell Holders:
.380 Lee = #4, RCBS = #10
9mm MAK Lee = #19, RCBS = #1
9mm Luger Lee = #6 or #19, RCBS = #1
.40 S&W Lee = #19, RCBS = #27

As you can see, RCBS makes specific shell holders that fit right.
Lee, not so much.

rcmodel

it would probably not be catastrophic to load a 9MM load in a .380 case,

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I believe it might be.

If it fired, the .380 case would almost certainly fail at 9mm pressures.

A .380 at normal .380 pressure, fired in a 9mm is a non-event resulting in a bulged case.
But it likely wouldn't be at full+ 9mm pressure due to the reduced case volume.

rcmodel

I did that once. Case didn't fail, but the primer pierced, indicating to me a severe overpressure situation. Bottom line, I wouldn't do it, and if one slips through and loads (which will sometimes work, despite the .380 being loose in the shellplate) pull the bullet and discard the case. You don't want to fire it in your gun.

had a 380 nestle inside a 357 that went unnoticed to the depriming die where it promptly mated perfectly to the decapping stem. took a dremel to separate the two. and 32acp are like terrorists--they are everywhere and yet they hide.
i'm not liking Murphy.

No speculation necessary. I performed the experiment.

As mentioned, you need to inspect your brass better, my friend.

As a purposeful experiment I've loaded 9mm loads into 380 cases and fired them in a 9mm Beretta. They all shot fine, no sign of blow up. And they all reloaded again afterward. Of course, they chambered off the extractor so I cleaned the chamber very carefully afterward (copper/lead shavings on the headspace ledge).

I don't advocate that you experiment.

I do advocate that you check your brass better.

+1 With Ants

OMG, Boys! The question was

What happens if you accidently load a 9mm bullet in a .380, 9x18 or other dimensionally similar case?

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Stop kicking butt for an honest question. You're gonna make people not want to ask - and that's not why people are here.

The answer is, it just may chamber and fire. I did it too, for certain once, maybe twice. YES, you should be able to notice something's wrong when you run it up as a load - I use a progressive - but also when you load it into a mag. I've found a couple 9mm loads in .380 brass in my own loads and pitched them.

The one or two that did fire functioned normally, no signs of excess pressure (although in the smaller case, I KNOW it was higher). The 9mm loads weren't very hot loads, but I wouldn't do it on purpose. The case was stretched on the one I did notice.

ahhh.... why are you lubing 9mm cases? not usually necessary for straight cased ammo.

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If you ask that question, you haven't tried it (hint try it at least once).

i use the same shell holder for 9mm 9mm mak and 40sw- and I'm pretty sure 380 goes in there are well.

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There is a .020" difference between the rim on a 9X19 and a .380 (the .380 and .223 use the same shell holder). 9mm and .40 are different as well, .030" difference


I’ve seen people shoot .40 out of a 45 and 9mm from 40 and even once a 264 win mag from a 300 Weatherby. Nothing blew up and no one got hurt. I prefer to take luck out of the equation and case gauge my ammunition. Both .380 and 9X18 fall well below the top edge of the case gauge.

ahhh.... why are you lubing 9mm cases? not usually necessary for straight cased ammo.

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The 9x19 is a tapered case, and lube makes sizing them very easy

The 9x19 is a tapered case, and lube makes sizing them very easy

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I'm sure they are but I have found them very easy to size without lube. For me it is a waste of time to have to remove lube from something that didn't need lube to begin with but that's just me.
Rusty

I lightly lube .380 ACP and 9x19mmP cases in my carbide FL sizing dies...

Afterwards, I just wash them in hot soapy water (having used a water soluble case lube (RCBS Case Lube II))...

A small amount of lube makes sizing much easier and slicker...

Forrest

Loading 9mm P on a Dillon 550, I have seen the following odds and ends mixed in with "once fired" brass mailorered and tumbled but not sorted by headstamp:

1. .380 The case is untapered and thinner than 9mm P. It goes into the sizing die with no resistance, the press handle slams to the bottom. There is no doubt what is going on. Remove from the shellplate and put in the .380 brass box for later use.

2. 9x18 Makarov A true 9.2mm, the case is larger at the mouth than a true 9mm but is very close to the same head diameter as a 9mm P. There was a lot of Makarov ammunition loaded in trimmed 9mm brass before sources became available. There is no difference in the "feel" or operation of the press. The case goes through the entire loading process and is caught when gauging IDPA match ammo. Normally pulled down to salvage the components, I have run a couple through a 9mm pistol to see what happened. They fed, fired, and functioned normally in spite of a millimeter excess cartridge headspace.

3. 9x21. The Italian rule-beater round for use in jurisdictions that do not allow private ownership of "military" calibers. Same as 9mm P except longer brass. It sizes down normally, but flaring of the long case gives it a huge bugle mouth that is immediately obvious when going to the next station. Dump the powder and trash the case.
I have not run into a .38 Super, 9mm Largo, or 9x23 mixed in with 9mm P brass but would expect it to behave the same way.

4. .40 S&W Will enter a 9mm Dillon shellplate and be crushed by the sizing die. You won't do that but once, they are easy to spot as you take them out of the box you unloaded the tumbler into.

Reloading & finding 'em.

I have not run into a .38 Super, 9mm Largo, or 9x23 mixed in with 9mm P brass but would expect it to behave the same way.

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That is, huge bell on the toop end of the case - yep, that's exactly what they do. I've found all those in my 9mm Luger brass piles. The 380 stuff doesn't just go 'thump' in my press, but I likely have a different brand of dies.
They certainly do feel different, though, and I do the same thing - I remove the .380 case and stick it with the rest of the .380 stuff waiting its turn. I would have half expected the .38 Super to not fit quite so well, but as it happens, the dimensions are close enough that when I set up to reload 9mm Largo, they run through just fine.

I don't recommend using .38 Super brass mixed in with your Largo brass, but I loaded some light loads just to see how they'd function in my Star Super, and they cycle just fine. And my Super isn't one of those marked from the factory "9mm/.38" as I've heard some of them were.

On my Dillon, I catch it when I notice a case that is not necked. Thw powder funnel doesn't come down far enough to bell the case at all, and bullet seating is very difficult. Knowing this, I check all necks for proper bell as a way of ensuring proper cartridge length.

It will likely feed and fire. I've done that at least twice and could tell something was not quite right both times. One primer was pierced, the other was slightly bulged. My reloads are on the low side. No harm, but I of course try to not make a habit of it.

I use a LWD barrel so my brass does not expand as much. I reload on a Dillon SD. It's not always as easy to tell when resizing the 380 when shooting light 9mm reloads in a tight chamber depending on the brass (i.e. brass is not equal and some expand more than others).