Emergency use of wrong caliber

[Lumpy]

In a crisis, could I get away with shooting 9mm from a .40, if I hand-chambered each round?

[MJY65]

They will generally go off if the extractor has enough tension to hold the cartridge against the breech face, accuracy will be horrible and velocity will be severely compromised.

[ttousi]

my experience is that a 9mm will fire but not eject from a 40

also same situation with a 380 vs 9mm

seen them both

[Sigfan220]

I think you would be better off grabbing a shovel or hammer. I would think even if you could get the gun to go off the velocity would not be enough to do any kind of damage. Maybe in a case where they were the same diameter like 380 in a 9mm but not a 9mm in a 40.

[Lumpy]

I think you would be better off grabbing a shovel or hammer. I would think even if you could get the gun to go off the velocity would not be enough to do any kind of damage. Maybe in a case where they were the same diameter like 380 in a 9mm but not a 9mm in a 40.

.40 in a 10mm?

[westhope]

I have RO'ed several shooters in IDPA & IPSC matches over the years that have shot 9 mm out of a 40 SW.

The round fired, put a hole, usually oblong, in targets 7 to 10 yards away.

The gun would not cycle automatically. They would cycle by hand.

Yes, the extractor holds the 9 mm enough for the round to fire in a 40 SW.

The shooters usually have two of the same style guns and got them mixed up.

They really make an interesting case. 9 mm at the rim and 40 at the mouth of the case. I have several that I picked up.

[Sigfan220]

I think you would be better off grabbing a shovel or hammer. I would think even if you could get the gun to go off the velocity would not be enough to do any kind of damage. Maybe in a case where they were the same diameter like 380 in a 9mm but not a 9mm in a 40.

.40 in a 10mm?

Two straight wall cases of the same diameter shouldn't be a problem at all. As long as it can fire. The smith and wesson 610 was factory designed to shoot 40 and 10 as I recall. I couldn't find anything official now that it is out of production. Then again that used moon clips so it is essentially a rimmed case at that point(head spaces on the moon clip not the case mouth like in an auto).

The problem with 380 in 9mm is 9mm is actually a tapered case, they are not the same rim diameter. But at lease they are the same bullet/bore diameter. I would thing a lot of gas would escape out the chamber and pressure would be low.

I agree a 9mm in a 40 would punch a hold in paper. It however may not have enough power to penetrate skin or at least enough to do any real damage. Without a seal around the bullet I would think the velocity would be in the wrist rocket/sling shot range.

[crbutler]

In auto pistols, assuming a straight wall cartridge, using a smaller bullet diameter than the bore will go bang, but likely not disable an opponent. I have seen the bullet sticking in the target within 20 yards. Bad idea, and potentially unsafe if you develop a bore obstruction.

Using a shorter cartridge with the same diameter can give headspace issues, but if it goes off, more often than not it will function the gun and perform like a round from the shorter cartridge weapon.

A .380 in a 9x19 or a 9x23 will develop .380 ballistics more or less, same with a .40 in a 10mm. As long as your extractor has enough tension and is not too dissimilar in power to the original chambering, it will work like a firearm. Target rounds won't typically work the action, but stouter SD rounds will. The big caveat is some guns like the 9 largo have substantially lower pressures than a modern 9mm and you can have a "spontaneous dissassembly" if th short round is too high pressure. Don't pick up some 9 largo ammo on the ground at a range around here and stuff it in a Star destroyer because lots of guys use that in race guns and it is loaded to 65,000+ PSI.

Revolvers this is often thought of as versitility. You can shoot .45 colt, .454 casull, and .460 mag out of a SW 460 revolver.

[Seismic Sam]

In a crisis, could I get away with shooting 9mm from a .40, if I hand-chambered each round?

I agree with the poster who said you'll be stone cold dead and turning green before you can get a shot off by trying this. Plus your accuracy will suck so bad you might as well have gone with holding the gun sideways and hollering "BUS' caps, YO!!! to stop the attack.

The other point which is being missed here is that everybody assumes that it takes a REAL idiot to take a 9mm round and chamber it in a 40, despite the fact that multiple people have found cases shot with a 9mm rim and a 40 caliber case mouth. This mistake, however, is NOT what actually happens. I did a simple test based on an EAA 10mm mag (because I fart in the general direction of all 40's and don't own one), and found out that 9 mm cases will not STAY in a 10mm mag!! Try it, and please report back if you can get a 9mm round to STAY in a 40 S&W mag securely enough to have the mag slapped into the gun and the slide dropped on it. Also report if the 9mm round stays in the chamber or dribbles down the barrel.

To cut to the chase, the people who are producing all these "idiot cases" are probably n00bs who don't know diddly squat about their guns, but own 1 in 9mm caliber and 1 in 40 S&W caliber and the guns are the same BRAND, AND the mags are the same or nearly the same size!! In THIS case, if you have a bag of loaded mags (which is common), and reach into the bag and come up with a 9mm instead of a 40 mag and slap it into the gun. If it goes boom!! (even sorta), you may not realize what happened.

So to get back to you, Lumpy, if it's a SHTF scenario and you have 9mm ammo, you are going to need a 9mm MAG for that pistol. If you don't have one on you, you are going to have to excuse yourself from the festivities, get in your car and drive home, find a 9mm mag that will fit, and then drive back to the scene of the crime.

There is actually a system out there that is DESIGNED to work this way, and it's the SIG P226 in 357 Sig caliber. Now while the 357 SIG has the base of a 40 S&W case, it shoots 9mm rounds, AND you can buy a "special" 9mm barrel for that gun which allows the 40 caliber extractor to work on a 9mm rim and barrel, and if you stuff a 9 mm mag in this gun you can merrily shoot 9mm rounds all day, and the brass comes out fine too!

[linksep]

.40 in a 10mm?

The Truth About Guns: Why I Shoot .40 Through My Unmodified 10mm GLOCK

[igofast]

The other point which is being missed here is that everybody assumes that it takes a REAL idiot to take a 9mm round and chamber it in a 40, despite the fact that multiple people have found cases shot with a 9mm rim and a 40 caliber case mouth. This mistake, however, is NOT what actually happens. I did a simple test based on an EAA 10mm mag (because I fart in the general direction of all 40's and don't own one), and found out that 9 mm cases will not STAY in a 10mm mag!! Try it, and please report back if you can get a 9mm round to STAY in a 40 S&W mag securely enough to have the mag slapped into the gun and the slide dropped on it. Also report if the 9mm round stays in the chamber or dribbles down the barrel.

...

There is actually a system out there that is DESIGNED to work this way, and it's the SIG P226 in 357 Sig caliber. Now while the 357 SIG has the base of a 40 S&W case, it shoots 9mm rounds, AND you can buy a "special" 9mm barrel for that gun which allows the 40 caliber extractor to work on a 9mm rim and barrel, and if you stuff a 9 mm mag in this gun you can merrily shoot 9mm rounds all day, and the brass comes out fine too!

I have loaded up a Sig P229 .40 cal mag with 9mm(and a P228 9mm upper) and cycled the full mag, no issues.

There's lots of 'conversion barrels' out there for various guns to convert .40 to 9 - Glock, M&P, etc.

[smurfman]

I have a 9 mm conversion barrel for my XD 40. The barrel is slightly off center so the extractor has a good grip on the case. I believe that is common in such cases as the 40 cal extractor does not reliably grip all 9 mm brass.

In my gun the 9 mm barrel is much more accurate than the original barrel in spite of the barrel being offset. The Springfield 40 cal mags do not hold 9 mm rounds but the blued aftermarket mags I picked up will hold some 9 mm rounds but they are easily ejected if jostled.