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View Full Version : My .40 will chamber a .357 sig


TurboChrisB
06-23-2010, 4:56 PM
So I already had a SigPro 2340 in .40....today I picked up another Sig 2340 in .357..since the mags are interchangeable I was curious as to what happens if you put a mag with .357 into the .40 and vice versa...well, I can rack it and chamber a .357 into the .40 but not the .40 into the .357...

So now I'm curious what would happen if someone chambered a .40 with a .357 round and pulled the trigger? Would nothing happen or would I get the big bang with ugly results? Anyone know? Surely someone must have done this accidentally before...

toby
06-23-2010, 5:05 PM
You really should'nt have to ask?,,,,,:rolleyes:

RobG
06-23-2010, 5:05 PM
Seriously? This has to be a trick question:confused::eek:

Sinixstar
06-23-2010, 5:11 PM
Let's think about this real hard.

Gun is chambered for .40 S&W, you drop a .357sig in there.

.357sig =/= .40S&W

is there really any more that needs to be said?

kel-tec-innovations
06-23-2010, 5:22 PM
This happened with my Glock .40 and .357 and they use the same magazine and I accidental put a .40 into my .357 glock and I pulled the trigger but luckily the slide doesn't close all the way and the bullet didn't go off other wise it would be bad. I would imagine barrel damage if it goes off.

cgseanp1
06-23-2010, 5:23 PM
I must be an idiot cuz I don't know what would happen. Maybe one of those 3 guys that posted above could enlighten us since it's sooo obvious:)

railroader
06-23-2010, 5:30 PM
So I already had a SigPro 2340 in .40....today I picked up another Sig 2340 in .357..since the mags are interchangeable I was curious as to what happens if you put a mag with .357 into the .40 and vice versa...well, I can rack it and chamber a .357 into the .40 but not the .40 into the .357...

So now I'm curious what would happen if someone chambered a .40 with a .357 round and pulled the trigger? Would nothing happen or would I get the big bang with ugly results? Anyone know? Surely someone must have done this accidentally before...

Being the bottom half of your brass is 40 cal you would probably get away with. The neck might get resized up to 40 cal and the 9mm bullet would go rattling down the barrel. ;) Mark

Sinixstar
06-23-2010, 5:31 PM
I must be an idiot cuz I don't know what would happen. Maybe one of those 3 guys that posted above could enlighten us since it's sooo obvious:)

The extent and severity could range anywhere from simple malfunction all the way to deadly catastrophic failure.

Does that make it clear enough?

yes, it should be painfully painfully obvious that you should only shoot ammo that your gun is chambered for. This is up there with "don't point a loaded gun at your own face and pull the trigger" in terms of proper gun handling as far as i'm concerned.

If you really have to ask about shooting the wrong caliber of ammo out of your gun - you very well may want to consider a hobby in stamp collecting instead of guns.

masameet
06-23-2010, 5:36 PM
Don't you need a different guide rod and barrel if using the same frame?

I was offered in trade a SIG P229 in .40 with a .357 barrel and guide rod but passed on it.

And late last year I let somebody shoot my .45. She was having a blast until she got a FTE. She handed my 1911 to me to clear it and darned if a spent casing wasn't stuck in the barrel. Turned out in reloading the empty mags, she'd slipped some .40 rounds in with the .45 rounds. The .40 round fired but the casing stuck. At that point I should have made her empty out all the mags she had loaded. Oh well. Live and learn.

toby
06-23-2010, 5:37 PM
I think there are some people that should not have firearms!..:eek:

RobG
06-23-2010, 5:38 PM
The extent and severity could range anywhere from simple malfunction all the way to deadly catastrophic failure.

Does that make it clear enough?
yes, it should be painfully painfully obvious that you should only shoot ammo that your gun is chambered for. This is up there with "don't point a loaded gun at your own face and pull the trigger" in terms of proper gun handling as far as i'm concerned.

If you really have to ask about shooting the wrong caliber of ammo out of your gun - you very well may want to consider a hobby in stamp collecting instead of guns.

This. If you fired a .357 thru the .40 barrel you may get lucky and just have it rattle down the barrel and exit erratically. Now think about that .40 caliber bullet trying to travel thru a .356 diameter bore at 35500 cup. What do you think will happen?

Chief-7700
06-23-2010, 5:40 PM
So I already had a SigPro 2340 in .40....today I picked up another Sig 2340 in .357..since the mags are interchangeable I was curious as to what happens if you put a mag with .357 into the .40 and vice versa...well, I can rack it and chamber a .357 into the .40 but not the .40 into the .357...

So now I'm curious what would happen if someone chambered a .40 with a .357 round and pulled the trigger? Would nothing happen or would I get the big bang with ugly results? Anyone know? Surely someone must have done this accidentally before...

Might want to keep your ammo separated.

pepsi2451
06-23-2010, 5:41 PM
The extent and severity could range anywhere from simple malfunction all the way to deadly catastrophic failure.

Does that make it clear enough?

yes, it should be painfully painfully obvious that you should only shoot ammo that your gun is chambered for. This is up there with "don't point a loaded gun at your own face and pull the trigger" in terms of proper gun handling as far as i'm concerned.

If you really have to ask about shooting the wrong caliber of ammo out of your gun - you very well may want to consider a hobby in stamp collecting instead of guns.

He asked what would happen, not if it was a good idea. I don't really know what would happen but I would think railroader is probably right.

Being the bottom half of your brass is 40 cal you would probably get away with. The neck might get resized up to 40 cal and the 9mm bullet would go rattling down the barrel. ;) Mark

I definitely don't see anything good coming from it.

RobG
06-23-2010, 5:42 PM
Might want to keep your ammo separated.

Excellent idea. Shoot one then put it and all the ammo away before pulling out the other:thumbsup:

CSACANNONEER
06-23-2010, 5:49 PM
WOW. Someone needs to learn a bit more about their guns BEFORE an accident happens. It's obvious that the OP needs to better educate himself but, no one has bothered to answer the question yet. The answer is that the bullet will bounce down the barrel and leave it in the general dirrection the barrel is pointing. It will not hurt the gun or the shooter but, there is no reason to do it. All a .357sig is is a necked down .40S&W.

cgseanp1
06-23-2010, 5:51 PM
The extent and severity could range anywhere from simple malfunction all the way to deadly catastrophic failure.

Does that make it clear enough?

yes, it should be painfully painfully obvious that you should only shoot ammo that your gun is chambered for. This is up there with "don't point a loaded gun at your own face and pull the trigger" in terms of proper gun handling as far as i'm concerned.

If you really have to ask about shooting the wrong caliber of ammo out of your gun - you very well may want to consider a hobby in stamp collecting instead of guns.

Let's get a few things straight here. I personally know to NEVER try to shoot a caliber my gun isn't made for.. Doesn't mean I'm not curious what would happen. Since this bullet is smaller than what the gun was meant for, I wasn't sure. Is that clear enough for you?
I think there are some people that should not have firearms!..:eek:
Good one.
This. If you fired a .357 thru the .40 barrel you may get lucky and just have it rattle down the barrel and exit erratically. Now think about that .40 caliber bullet trying to travel thru a .356 diameter bore at 35500 cup. What do you think will happen?

He wasn't talking about firing a .40 out of a .357, it was the other way around. I (in italics) know what would happen if he was trying to fire a .40 out of a .357, just not the other way around. Now I know.

RobG
06-23-2010, 5:53 PM
Let's get a few things straight here. I personally know to NEVER try to shoot a caliber my gun isn't made for.. Doesn't mean I'm not curious what would happen. Since this bullet is smaller than what the gun was meant for, I wasn't sure. Is that clear enough for you?

Good one.


He wasn't talking about firing a .40 out of a .357, it was the other way around. I (in italics) know what would happen if he was trying to fire a .40 out of a .357, just not the other way around. Now I know.

I know, just throwing it out there. As he said, it wouldn't chamber anyway.

Sinixstar
06-23-2010, 6:01 PM
He asked what would happen, not if it was a good idea. I don't really know what would happen but I would think railroader is probably right.



The .357sig is a necked down .40 - so it's possible the round would just rattle down the barrel. personally - i'm not sure the brass is going to hold up to the 40,000 PSi fire forming to the .40 chamber, and would likely fail, and likely catastrophically.

that is just my opinion though, i have zero direct experience firing a .357sig from a .40 pistol. ;)

cntrolsguy
06-23-2010, 6:08 PM
Actually I think that this is a valid question considering that (not 100% sure) the mags are identical and would accept either round.

toby
06-23-2010, 6:15 PM
The 357 sig will fire form but ? it could also seperate or just spilt down the side wall all in all prolly all will come out fine BUT!!...things can go bad I have some 7x57 cases someone fired in a 30-06? why I don't know? what happened to the gun I don't know? the cases are now straight wall and cracked.

Corbin Dallas
06-23-2010, 6:24 PM
I must be an idiot cuz I don't know what would happen. Maybe one of those 3 guys that posted above could enlighten us since it's sooo obvious:)

Actually, nothing would happen.

The 357sig round would end pushed farther down the barrel by the extractor and the firing pin would probably not make contact.

Although you might get lucky and the round will get caught by the edge of the extractor and the firing pin will work as intended.

Pretty simple stuff.

I've seen 9mm rounds go down 40 barrels with no ill effects.

Interloper
06-23-2010, 6:29 PM
... Now think about that .40 caliber bullet trying to travel thru a .356 diameter bore at 35500 cup. What do you think will happen?

I doubt a .40S&W would even chamber in a .357Sig barrel.

CSACANNONEER
06-23-2010, 6:54 PM
I doubt a .40S&W would even chamber in a .357Sig barrel.

It can't. The .40 case would stop at the chamber's neck.

Grumpyoldretiredcop
06-23-2010, 7:42 PM
.357 Sig in a .40 barrel? Seen it. Weak report, bullet falls from muzzle to ground, well short of target. Officer looks at pistol, manually cycles slide, empty case is ejected. Case mouth partially expanded, but not to .40 dimensions. Glock pistol undamaged; red-faced officer goes back to ammo table, carefully unloads magazines and removes .357 ammo. Reloads with correct ammo, qualifies and leaves.

.40 in .357 Sig? Seen that, too. Officer inserts magazine, releases slide, slide stops well before going into battery. Officer ejects that round, tries again. Same result. Another rangemaster and I come over, inspect pistol, ask why she is attempting to use .40 in a .357 Sig pistol. Sig pistol undamaged. Red-faced officer goes over to ammo table, unloads magazines, carefully deposits .40 ammo in proper box, reloads with .357 ammo, proceeds to qualify.

Red-faced rangemasters do better job of widely separating .40 and .357 Sig ammo after that. :D

pepsi2451
06-23-2010, 7:57 PM
.357 Sig in a .40 barrel? Seen it. Weak report, bullet falls from muzzle to ground, well short of target. Officer looks at pistol, manually cycles slide, empty case is ejected. Case mouth partially expanded, but not to .40 dimensions. Glock pistol undamaged; red-faced officer goes back to ammo table, carefully unloads magazines and removes .357 ammo. Reloads with correct ammo, qualifies and leaves.

.40 in .357 Sig? Seen that, too. Officer inserts magazine, releases slide, slide stops well before going into battery. Officer ejects that round, tries again. Same result. Another rangemaster and I come over, inspect pistol, ask why she is attempting to use .40 in a .357 Sig pistol. Sig pistol undamaged. Red-faced officer goes over to ammo table, unloads magazines, carefully deposits .40 ammo in proper box, reloads with .357 ammo, proceeds to qualify.

Red-faced rangemasters do better job of widely separating .40 and .357 Sig ammo after that. :D

LOL wow it seems like that would be a hard mistake to make since one is a bottleneck cartridge and one is not, you would think a cop would shoot enough they would notice something like that. I could see if you had the same gun chambered in both and grab the wrong mag but how do you load your mag with the wrong ammo?.

masameet
06-23-2010, 8:10 PM
Well, now that we know what happens when .357 and .40 rounds are interchanged and fired into the wrong caliber barrels, here is the spent casing of a .40 round fired through a .45 barrel:

http://i201.photobucket.com/albums/aa184/masameet/40Casing_7884v3.jpg

Beautiful, ain't it?

TurboChrisB
06-23-2010, 10:07 PM
Wow, some of you guys are really too much.. Was it really that difficult to understand my post? I didn't ask if I COULD do it, nor did I state that I wanted to or was planning to...I asked that since the WRONG caliber would EASILY chamber in my gun...what, HYPOTHETICALLY, would happen if they in fact tried to fire the gun....maybe some of you should read the post twice before you answer guys. :rolleyes:

Doheny
06-23-2010, 10:14 PM
The answer is that the bullet will bounce down the barrel and leave it in the general dirrection the barrel is pointing. It will not hurt the gun or the shooter but, there is no reason to do it. All a .357sig is is a necked down .40S&W.

This. Frankly, no biggie, but don't make a habit of it. I've mistakenly fired a 9mm through my .40 before, which is essentially the same thing as a .357 sig through a .40 (yes, I need to keep my ammo seperated.) Just a 'pop" with little recoil. When you eject the casing you'll find that the neck blossomed out.

Grumpyoldretiredcop
06-23-2010, 10:51 PM
Wow, some of you guys are really too much.. Was it really that difficult to understand my post? I didn't ask if I COULD do it, nor did I state that I wanted to or was planning to...I asked that since the WRONG caliber would EASILY chamber in my gun...what, HYPOTHETICALLY, would happen if they in fact tried to fire the gun....maybe some of you should read the post twice before you answer guys. :rolleyes:

.357 Sig in a .40 barrel? Seen it. Weak report, bullet falls from muzzle to ground, well short of target. Officer looks at pistol, manually cycles slide, empty case is ejected. Case mouth partially expanded, but not to .40 dimensions. Glock pistol undamaged; red-faced officer goes back to ammo table, carefully unloads magazines and removes .357 ammo. Reloads with correct ammo, qualifies and leaves.

Okay, I did answer realistically instead of hypothetically... but I really did read your post. :D

LOL wow it seems like that would be a hard mistake to make since one is a bottleneck cartridge and one is not, you would think a cop would shoot enough they would notice something like that. I could see if you had the same gun chambered in both and grab the wrong mag but how do you load your mag with the wrong ammo?.

Because some cops aren't "gun folks" and can as easily do that as I can grab the wrong hammer to do some amateur carpentering. You should see what happens when the 9MM and .40 S&W boxes are too close together. That isn't pretty at all.

TurboChrisB
06-23-2010, 10:54 PM
Present company excluded :D

Doheny
06-23-2010, 11:32 PM
/\/\ You probably know this, but a .357 Sig is a .40 crimped down to accommodate a 9mm bullet. That's why the .357 fits in the .40; the larger part of the casing is the same, but the .357 Sig bullet is smaller than the .40.

The reason it's called a .357 Sig is because the ballistics are supposed to be similar to a .357 magnum. Sig is the one who designed the round, but Glock actually made the first gun to accept it.

As far as trying to put a .40 in a .357 Sig, you won't be able to do it. That's because as I said, the .357 Sig uses a 9mm bullet which is smaller than the .40; it simply won't fit.

.

randy
06-24-2010, 12:37 AM
Being the bottom half of your brass is 40 cal you would probably get away with. The neck might get resized up to 40 cal and the 9mm bullet would go rattling down the barrel. ;) Mark

Correct. Your gun most likely won't cycle. The brass fire forms to the 40 chamber and the bullet rattles down the barrel. You won't blow anything up as the pressures are greatly reduced. The bullet won't fill the barrel and the gas will escape ahead of the bullet.

If you put a 9mm in a 40 or a 40 in a 45 same thing. It is best to make sure the bullet did leave the barrel before shooting another round.

Ed_Hazard
06-24-2010, 12:45 AM
See all the fun your getting out of that sigpro? And you have not even been to th range yet. Ed

TurboChrisB
06-24-2010, 1:35 AM
hahahahaha, Thanks Ed! I'll be taking it along with a few others out to Barstow Sat to play....think I'll see if I can fire some .308 out of it. :D

Interloper
06-24-2010, 8:52 AM
Wow, some of you guys are really too much.. Was it really that difficult to understand my post? I didn't ask if I COULD do it, nor did I state that I wanted to or was planning to...I asked that since the WRONG caliber would EASILY chamber in my gun...what, HYPOTHETICALLY, would happen if they in fact tried to fire the gun....maybe some of you should read the post twice before you answer guys. :rolleyes:

Your post was read and answered, then conversation developed from there. Looks like you didn't actually read any of the replies.

TurboChrisB
06-24-2010, 10:28 AM
Obviously YOU didn't read them and still aren't, as your only previous post in this thread was stating something as probable that I had already made CLEAR in my opening post. Impressive.

And to those who DID understand my question and answered it correctly.....Thanks!

Interloper
06-24-2010, 11:17 AM
Obviously YOU didn't read them and still aren't, as your only previous post in this thread was stating something as probable that I had already made CLEAR in my opening post. Impressive.

And to those who DID understand my question and answered it correctly.....Thanks!

Is it written somewhere that I'm required to read your boring posts? I was participating in a far more interesting discussion. You should be flattered that your OP didn't result in a single technically correct answer and no further discourse. Damn dude, chill out.

TurboChrisB
06-24-2010, 11:41 AM
Yeah, I am a bit stressed this morning........Cheers!

Interloper
06-24-2010, 11:43 AM
Yeah, I am a bit stressed this morning........Cheers!

Now you made me feel bad about being a jerk. Gimme a hug, brother.

Doheny
06-24-2010, 12:08 PM
:grouphug:

TurboChrisB
06-24-2010, 12:12 PM
Hahahahaha :thumbsup:

IEShooter
06-24-2010, 12:14 PM
.357 Sig in a .40 barrel? Seen it. Weak report, bullet falls from muzzle to ground, well short of target. Officer looks at pistol, manually cycles slide, empty case is ejected. Case mouth partially expanded, but not to .40 dimensions. Glock pistol undamaged; red-faced officer goes back to ammo table, carefully unloads magazines and removes .357 ammo. Reloads with correct ammo, qualifies and leaves.

.40 in .357 Sig? Seen that, too. Officer inserts magazine, releases slide, slide stops well before going into battery. Officer ejects that round, tries again. Same result. Another rangemaster and I come over, inspect pistol, ask why she is attempting to use .40 in a .357 Sig pistol. Sig pistol undamaged. Red-faced officer goes over to ammo table, unloads magazines, carefully deposits .40 ammo in proper box, reloads with .357 ammo, proceeds to qualify.

Red-faced rangemasters do better job of widely separating .40 and .357 Sig ammo after that. :D

This is good information. Thanks for posting.

I'm sure this actually happens more than people think. I have a Glock 22 chambered in .40, but I also have a 9mm and .357 Sig barrels for it along with appropriate magazines. I routinely shoot all three out of it.

I'm not surprised that the .40 won't chamber in the .357 sig barrel.

While I've never mixed them up, I bet others have.

Regards,

John

DVSmith
06-24-2010, 12:25 PM
Well, now that we know what happens when .357 and .40 rounds are interchanged and fired into the wrong caliber barrels, here is the spent casing of a .40 round fired through a .45 barrel:

http://i201.photobucket.com/albums/aa184/masameet/40Casing_7884v3.jpg

Beautiful, ain't it?

That seems to happen surprisingly often. We have had students that bring their own bulk ammo end up feeding .40 into a .45 with quite similar results. As much as we inspect their ammo before practical exercises, you can't look at every round. The only solution we have come up with is making students bring factory packed ammo, but we have not gone that far yet.