Firing .40 in a Glock 10mm.

[robsguns]

I just was reading an old post on here from 2011. Seems there were a lot of folks ridiculing some members about their idea that firing a .40 cartridge from a 10mm Glock is dangerous. So anyway, I believe that it has been proven to be perfectly safe over the past several years, and there is enough evidence to sustain the claim without bashing folks for talking about it. Here is some bed time reading for you guys, and some videos as well with some more reading in the comments sections. http://www.thetruthaboutguns.com/201...-a-10mm-glock/ https://www.youtube.com/watch?v=Vi7zJ6agymo https://www.youtube.com/watch?v=AwXtEm70Q0M

[Lohman446]

Why would you outside of an emergency?

[James K]

Why? Possibly for the reasons given. Why not? I have no reason to doubt the information given in the link, but will note that firing a short cartridge in a gun made for a longer cartridge (like .45 GAP in a .45 ACP pistol) can always have problems not caused by lack of power (there is no significant difference in normal lads between 10mm and .40 S&W) but by such factors as the dimension of the magazine feed lips or the feed ramp. I wouldn't do it (except in an emergency) without a lot of testing with a particular gun.

I can see no reason for any danger in doing so.

Jim.

[Cheapshooter]

Why?
I bought a 10 MM because I wanted a 10 MM. If I want to shoot 40 S&W I'll shoot my 40 S&W
Maybe there's a demand for a Corvette with a Chevy Cruze engine.

[Slimjim9]

Why? For the same reason I mostly shoot 38s in my 357. Cheaper and (arguably) funner, at least for extended sessions. I don't have a .40 or a 10mm, but thie ability to fire either in the same gun would be a big factor if I decided to get one.

[JohnKSa]

It will certainly work, and it's true that it's not extremely likely to ruin the gun or be unsafe. But it's also true that there is some potential for damage/danger.

Bullet material can be shaved/scraped off at the chamber mouth and may build up enough to create a partial obstruction.

Normally the case mouth is at the chamber mouth and there's no way for the lip at the chamber mouth to shave bullet material. When you fire a shorter round in an autopistol chamber the case mouth is back from the chamber mouth. That means the bullet is coming from far enough back that it can hit that lip and shave bullet material.

In a revolver chamber, the front of the chamber tapers so there's no possibility of shaving bullet material.

There's also some potential for headspace issues since extractors aren't generally specified to insure that they maintain proper headspace.

http://www.thegunzone.com/10v40.html

There are some other potential issues as well.

http://wethearmed.com/handguns/shoot-40-sw-in-a-10mm/

I tried it. Ended up with blown primers, which is a chamber depth issue rather than a pressure issue. The case is headspacing on the extractor, so it's got a lot of wiggle room. You get extreme pressure signs but it's from the case slamming back into the breech face.

http://www.migunowners.org/forum/arc.../t-184956.html

I have fired .40 S&W in factory 10mm barrels, in both Glock 20s and Glock 29s. ... During this experimentation, I cracked an extractor in a Glock 29 and then found serious wear on the working face of my Glock 20 extractor.

You can play the odds. A lot of people do and get away with it.

Another option is a conversion barrel. .40S&W conversion barrels for 10mm Glocks are available for as little as $100.

For the same reason I mostly shoot 38s in my 357

That's very different.
1. The chamber mouth of a revolver is tapered. No possibility of shaving bullet material.
2. Revolver cartridges headspace off the rim, not off the case mouth. A shorter cartridge in a revolver won't have headspace problems nor will it rely on the extractor to hold it in place.

[Clark]

I have a Glock 20 that in Oct 2014 I went out in the desert to shoot some really hot load 200 gr Nosler Power Pistol 1.28" work up with a KKM G20 40sw barrel and a 22 pound recoil spring assembly I built.

I would have been better off with my Bar-Sto 10mm barrel to shoot my 40sw work up.
I forgot to throat the chamber for the longer bullet seating.
I did not get far before I had a case failure.

Power Pistol knows when I jammed into the lands.

[jetinteriorguy]

Um, someone please correct me if I'm wrong and I'll learn something new today. In a revolver the chamber is not tapered, the forcing cone is, which is part of the barrel not the chamber. The chamber is in the cylinder and is not tapered, at least not in my revolvers.

[Guv]

I agree with the barrel swap, $100.00 is cheap insurance. JohnKSa made some very fine points.

[Lohman446]

The last 10MM ammo I purchased was $16.95 a box after shipping. I can save roughly $2 a box by shooting .40. How much ammo is one shooting that $2 a box is of great enough importance to ignore the manufacturers advise not to do it?

[45_auto]

Originally Posted by jetinteriorguy

Um, someone please correct me if I'm wrong and I'll learn something new today. In a revolver the chamber is not tapered, the forcing cone is, which is part of the barrel not the chamber. The chamber is in the cylinder and is not tapered, at least not in my revolvers.

Then either your revolvers are chambered for cartridges that headspace on the mouth (forward edge) of the case (45 ACP, 9mm, 10mm, etc) or, if your revolvers are chambered for rimmed cartridges (.38 Special, 357 Mag, etc), your chambers are not cut to SAAMI specs.

SAAMI spec for a .357 is here (bottom pic, top is cartridge):

http://www.saami.org/pubresources/cc...7%20Magnum.pdf

Note the taper that starts in the chamber (no sharp lip) 1.3019" from the breech face, which leads into the chamber throat.

A .38 Special chamber has the taper starting at 1.163" from the breechface, which cleverly prevents the longer, higher pressure .357 Mag cartridges from chambering:

http://www.saami.org/pubresources/cc...ecial%20+P.pdf

SAAMI spec for a 10mm Auto is here:

http://www.saami.org/pubresources/cc...0Automatic.pdf

Note the sharp lip located at 0.992" from the breech face. A 10mm cartridge headspaces on that lip. A 40 S&W will be held against the breech face by the extractor (hopefully) a given distance from the sharp lip (about .992" - .850" = .142") and, as JohnKSA stated, that sharp lip is just waiting to shave your bullets and build up a nice ring in the chamber for you.

A 40 S&W chamber has the sharp lip for the cartridge to headspace against at 0.850" from the breechface:

http://www.saami.org/pubresources/cc...40%20SandW.pdf

[mannyCA]

I can see the op's point. Never know when you may need to but why do it? Plus, the "knowing" weighs nothing and was free

[robsguns]

I have done enough research on this subject, through the use of the internet, to know that there are a lot more shooters than I can count firing .40 (hundreds of rounds in most cases, thousands in others) out of their 10mm Glocks with no ill effects. Does that mean it is safe to do so, with no chance of ill effects? No, it doesn't, but no more so than firing 10mm out of a 10mm Glock, in my book anyway. I've seen more case ruptures and blown barrel chambers on a Glock 10mm from shooting 10mm through a Glock barrel than I can count. I have not seen anyone post pictures of this type of failure from firing .40 through a Glock 10mm barrel. If I were making a habit of doing this, and I broke an extractor, for what they cost, it would not bother me one bit, after saving the amount of money I would have, firing .40 over 10mm. Will I regularly fire .40 through my 10mm Glock barrel? No, because I have handguns chambered in .40 for that, Glocks included, so I have no need to buy a conversion barrel for my 10mm Glock, or fire .40 through my 10mm Glock. However, it is nice to know that if I am in a jam, in my book anyway, it is just as safe to use the .40 as what I would expect it to be firing the 10mm. I knew this would be a topic that would generate conversation, but I wanted to bring it up again, in light of the previous thread on it from 5 years ago getting almost nothing but negative comments, and see if the passing of time would show a more favorable outlook on this practice today. I believe the comments do show that it is generally more accepted to be a practice that can be done, mostly in a situation dictating it as a matter of 'no choice', but at least it is being recognized as an alternative to being out of ammo when the 10mm ammo has been expended and the .40 ammo is still in the closet or truck and you are holding a 10mm in your hand. Thank you for all of the feedback, positive and negative.

[JDBerg]

All of the people I know personally who shoot 10mm reload for it at a significantly lower cost per round than the cost of any factory .40S&W. Arguably superior ballistics at a lower cost. A S&W 610 revolver will definitely shoot either caliber if a 10mm handloader wants to shoot some .40S&W out of the same gun.

[9x45]

Thousands of shooters do this for USPSA competition. The power floor is 165 so there is no need to run full house 10mm when you can run 40S&W.

[laytonj1]

I installed a Lone Wolf 40 S&W barrel in my Glock 20. Worked like a champ and no worries about headspacing.

A S&W 610 revolver will definitely shoot either caliber if a 10mm handloader wants to shoot some .40S&W out of the same gun.

You have to use moon clips to properly headspace the 40 S&W cartridges.

The last 10MM ammo I purchased was $16.95 a box after shipping

Where and when?

Jim

[Lohman446]

Where and when?

Jim

SGAmmo.com - Sellier and Bellot 10MM. Last week. $14.95 a box - I ordered 6 boxes and shipping was $12. I think its $1 off per box if you order in quantity. The ammo has come in and out of stock at least twice in the last month so it seems they have a supply of it somewhere.

[stagpanther]

Agree with JohnK--I'm no expert but I own and have shot a glock 20 for a long time. My experience with cartridges with varying headspace in the glock is that mostly you'll be OK--but in general not a good idea IMHO. given the different case length dimensions there is inherent unpredictability IMO as to how well the case will seal to the chamber--not to mention primer strike reliability.

[Lohman446]

Thousands of shooters do this for USPSA competition. The power floor is 165 so there is no need to run full house 10mm when you can run 40S&W.

What is the purpose in buying a gun that fires a caliber different then the one you will commonly use? I guess I am back to the "why" factor. If you want to shoot .40 there are many nice .40s out there to chose from.

[tipoc]

From the op:

I just was reading an old post on here from 2011. Seems there were a lot of folks ridiculing some members about their idea that firing a .40 cartridge from a 10mm Glock is dangerous. So anyway, I believe that it has been proven to be perfectly safe over the past several years, and there is enough evidence to sustain the claim without bashing folks for talking about it

It can be done. Main question is why you would do it other than in an emergency.

I can bake a gun in a casserole, or into a batch of mac and cheese...but why?

I can also shoot 380 acp from a 9mm. 9mm from a 38 Super, 357 Sig from a 40 S&W, but why?

Because it can be done sometimes, does not make it a good practice. Should we advocate that if a fella wants a gun in 40 S&W they forgo that for the "2 round" gun? That all 10mms are now "40S&W/10mm" guns in the way that 38/357's are?

I also have to question the assumption that..."So anyway, I believe that it has been proven to be perfectly safe over the past several years"

It's that word "safe" that gets in the way. It assumes that 5,000 or more rounds of 40 S&W have been fired through a good many Glock 20s without incident of any type related to the round being shorter in overall length than the 10mm.

Shooting some rounds of 40 S&W from a 10mm gun does not make it a useful practice to encourage across the board or to declare that it's a good practice and a safe one, or as good as having a gun in 40 S&W.

Does this hold true for other guns or just Glocks? Should we encourage the same experiments from a S&W 1006 or a 1911 in 10mm?

Is it as reliable as 38 Spl. from a .357 mag, the 44 Spl. and the 44 Mag (guns which were specifically built for 2 rounds)?

Can we promote all 10mms as "safe" for 40 S&W?

If we can't then what's the point?

If the point is that oyu can do it sometime in a pinch...then OK.

There are benefits to shooting a gun in the caliber it was built for. It generally means reliability is enhanced. As the proper magazine enhances reliability. In the case of the 40 S&W the gun is smaller and lighter.

Those are my hesitations about recommending it as good practice.

tipoc

[amd6547]

I bought a police surplus 1006 a few years ago, and at that time, had a hard time finding 10mm.
Read a magazine review of the 1006 which mentioned that they shot 40s&w in it with no problems.
So, I tried it.
I also had no problem, and ended up shooting a couple hundred rounds through my 1006.

[Sevens]

What is the purpose in buying a gun that fires a caliber different then the one you will commonly use? I guess I am back to the "why" factor. If you want to shoot .40 there are many nice .40s out there to chose from.

This is a valid question and for me, it's extremely easy to answer:

For many years, 10mm was my choice for daily carry and regular practice with it is an important part of my routine (and for many or most who carry) and as are most 10mm fans, handloading is the way to go. As such, the 10mm brass is very important. You don't just "find" the stuff scattered anywhere and everywhere and it's odd enough that you also rarely see bags of used 10mm brass offered for sale.

.40 S&W brass is on the far, FAR other end of the spectrum. Next to 9mm brass, it's easily the MOST plentiful stuff on this planet. It's scattered everywhere and even many .40cal handloaders don't bend over backwards to pick the stuff up.

So wanting to run a favorite 10mm pistol with .40cal brass is almost a natural inclination for any 10mm fan, and we know going in that YES, it's not shooting exactly 10mm loads, but it still offers a lot of repetition and practice with the handgun itself, something that isn't replicated quite as well with a whole different handgun, especially when you are talking about a carry gun, a holster for it, etc etc.

Furthermore, especially for some of us who are long students of handloading and internal ballistics... .40cal specifically brings a different thought process to the load bench because it's early history was inundated with "over-pressure events" and problems associated with the cartridge itself and as much/more the platforms built for it. This subject takes off on a tangent very much away from the original topic, but it's absolutely relevant for some of us and the bottom line of it is... .40 S&W run from a 10mm pistol (rather than a .40 S&W pistol) is a fantastic idea if that's what you wish to do. Most/many .40cal pistols began life as 9mm guns adapted for a larger round, where 10mm pistols typically started life as .45cal-sized guns that were adapted for a smaller-diameter round.

Me, I carried a Glock 29 for more than 7 years and have run over 6,500 rounds through it. I bought a KKM .40 S&W barrel for it to handle .40cal ammo and my log reflects that 3,400 have been 10mm through the OEM barrel and 3,100 have been .40cal through the KKM barrel.

So to answer the quoted question, oh YES there are great reasons to buy any particular guns, even if it doesn't seem to occur to you quickly.

To answer the OP, I don't believe there is much of a safety risk in shooting .40cal ammo in Glock 10mm pistols, or in any 10mm pistols. However, I don't think it's a favor to the pistol, especially the extractor, and I won't do it. However, if I were going to do it, I think Glock is the best platform for it simply because Glock pistols are ugly, soulless, easily replaceable, easy to get parts for, and Glock pistols are extremely durable and a very good defense against poor use, bad practices, neglect and abuse.

I won't do it in any of my 10mm pistols, but you can bet your life I will never do it in my Smith & Wesson 1006.

[Lohman446]

I get the idea - I have a 10MM and have no ammo available so I'm going to shoot .40. But these people shooting thousands of rounds in competition... why did they not buy a dedicated .40 platform?

[Sevens]

10mm gun is usually a larger, heavier gun. Better for shooting in nearly every way than a similar gun that is smaller, lighter and shorter. This is not difficult to see.

And sometimes, it's not about what someone buys specifically for a task, but rather how they can use something they already have for a specific task.

[tipoc]

10mm gun is usually a larger, heavier gun. Better for shooting in nearly every way than a similar gun that is smaller, lighter and shorter.

That's a sweeping generalization isn't it? Is the larger heavier gun always better for shooting? What kinda shooting are you speaking of? Is it better for carrying 8-12 hours a day? What are you using the gun for? What's it's purpose? If so why not buy a all steel 40 S&W piece if you wish to shoot 40 S&W from a heavier piece?

Why not switch the 10mm barrel in a Glock for a 40 barrel and make the other adjustments needed?

Would you suggest that law enforcement begin to carry guns built for 10mm but load them with 40 S&W? If not why not?

tipoc