Glock 10mm

Based on what I've seen posted here and elsewhere, it appears that there are people who shoot .40 in their 10mm Glocks and seem to have no issues with it.

That said, my opinion is that when it comes to autopistols, you should shoot only the caliber marked on the pistol unless you are using caliber conversion parts. As far as I know, that's the advice you will get from all manufacturers as well.

When shooting .40S&W in a 10mm, there are some issues with certain parts of the gun (specifically the extractor) being stressed in ways that the designer didn't really intend, and also at least one potentially dangerous situation that can happen--although with very low probability.
 
Should be no issues switching barrels that I can think of though you may need to adjust the main spring weight if moving down from "real" 10mm power.
 
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I've done it with both a G20 and G29 with zero issues. In my case there is no difference in accuracy or point of impact. I've never had a single malfunction using 40 from the 10mm magazines.

But at the same time I see no reason to do it on a regular basis. I've done it enough to prove to myself that it will work and if I ever find myself in a situation where I have access to 40 S&W ammo, but not 10mm ammo I know it would work in an emergency.

I've not bought much ammo lately, but before things got crazy 10mm ammo was exactly the same price as 40 S&W locally. There was never as much on the shelf, but it was always available. I've never had a problem just buying 10mm. Most of the 40 S&W ammo I have was given to me by a buddy who sold his 40 and no longer needed the ammo.

Instead of buying another barrel for the 10mm it makes more sense to me to just buy a similar sized Glock in 9mm. The G20 is a tad thicker than a G17, but the trigger and all of the controls are exactly the same. Right now 9mm is the only handgun ammo readily available anyway.
 
People will tell you that you can shoot all sorts of cartridges out of all sorts of guns that weren't designed to shoot them. The key word here is "can" not "should" or otherwise "was designed to" shoot said cartridges.

I think the trick here is, some Glocks can cycle .40 S&W reliably while others cannot, but there are more folks who have discovered that their 10mm Glock can shoot/cycle .40 S&W and continue to do so that it has become known as something of an unlisted feature.
However, it's not something that Glock ever intended anyone to do, and if it were as safe or reliable as folks say it is, then I imagine that Glock would begin marketing it as a feature of their 10mm Pistols and even stamp the slides/barrels to reflect their ability to shoot both cartridges. It's just something that's possible because .40 S&W and 10mm Auto share a common lineage and are identical in all dimensions save for length, so the shorter .40 S&W "can" chamber in a 10mm and the heavier 180gr loads can even cycle because obviously any 10mm Pistol can shoot the average FBI Load which is basically just a 180gr .40 S&W load in a longer case.

Frankly, if folks plan on shooting mostly .40 S&W, then I think that it makes more sense to buy a Glock chambered in .40 S&W, and enjoy the benefit of carrying a smaller, lighter pistol rather than shooting it out of a 10mm Pistol just so that they can say that they own/shoot a 10mm Pistol.
Honestly, some 9mm Pistols can shoot .380 ACP Pistols, but you don't see anyone promoting it as a feature, nor does anyone really care because they can't use .380 ACP as a cheap substitute for 9mm Luger, much less does anyone brag about their ability to shoot the powerful 9mm Luger cartridge yet routinely chooses to shoot the weaker .380 ACP because it's honestly a bit uncomfortable for them to shoot 9mm Luger.
 
jmr40 said:
But at the same time I see no reason to do it on a regular basis.
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This.

If you're no longer interested in shooting 10mm, then buy a .40 Glock.

There are plenty of people that'll buy your unwanted pistol. You could even (gasp) trade it in on the pistol you want to shoot.
 
S&W-Keeper said:
Are you guys having any issues shooting .40 out of your model 20.I am trying to decide whether to get a .40 barrel.
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I'd get the lonewolf barrel conversion. Drops right in, you use the same mags. I shoot mine all the time

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I'm not sure any manufacturer recommends or even suggests conversion kits, specifically, unless they are made by them (CZ or Tanfoglio for example). I could be wrong, but I don't think Glock has ever advertised the modular calibers as a feature?

If it's just a risk to the extractor, maybe valid, okay. Extractors can be funny things. That's a replaceable piece.

Will it function, probably. A spring and extractor only issue again in a Glock 10mm.

Will it kaboom? Probably not. It shouldn't rupture a case. Alternatively, I've never read it's a wear up to kaboom. Meaning, if 40 is going to rupture in a 10mm barrel, your odds of it happening are each first time, not cumulative build up to an issue. I don't think there is a logical reason why it would.

But gosh darn, I like reliability and my fingers more than 100 dollars...
 
I'm not sure any manufacturer recommends or even suggests conversion kits, specifically, unless they are made by them (CZ or Tanfoglio for example)...
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I don't see that it would make any difference who made the conversion kit, but that's moot.

I wasn't trying to say that manufacturers recommend conversion kits, the point was that manufacturers will tell you to shoot the caliber marked on the pistol. I do know that at least some manufacturers will sort of tacitly acknowledge that people are doing conversions and speak up about which ones are not acceptable, implying that others are. Beretta, for example, used to recommend against doing a .357SIG conversion to the Beretta 96 pistols, but I never heard them speak against doing a 9mm conversion to one.
If it's just a risk to the extractor, maybe valid, okay. Extractors can be funny things. That's a replaceable piece.
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It is, and in a range use only gun, it's not a big deal if one breaks. I would say that the risk comes if this is done in a self-defense gun, and the additional stress results in the part breaking later, perhaps during a self-defense situation. Not saying that's likely because it's not--just saying that just because a part is easily replaced doesn't necessarily mean that breakage is acceptable.
Will it kaboom? Probably not. It shouldn't rupture a case. Alternatively, I've never read it's a wear up to kaboom. Meaning, if 40 is going to rupture in a 10mm barrel, your odds of it happening are each first time, not cumulative build up to an issue. I don't think there is a logical reason why it would.
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The potential issue comes from the fact that there's a sharp transition at the front of the chamber.

That "ledge" can shave bullet material and if it builds up, it can act like a partial obstruction, causing a dramatic increase in discharge pressures. I don't know how to assess how likely that is, but based on the fact that we aren't being assailed by horror stories about it, I would say it's not very likely. But it's something to keep in mind.

The other issue is that buildup and the chamber rings that can result from firing a short cartridge in a longer chamber might eventually result in issues with chambering the native round. That's not a catastrophic issue unless there's enough buildup that it interferes with bullet release by jamming the case mouth into the front of the chamber where the buildup constricts the case mouth. If the case mouth is constricted enough, that can increase discharge pressure.

If I were in some sort of an emergency situation and I had .40S&W ammo and a 10mm autopistol, I wouldn't have any second thoughts about loading up with .40S&W because as far as I can tell the odds of anything really unpleasant happening are quite small. But it's not something I would do routinely--although, as I said up front, I know that others do and seem to get away with it.
 
My first 20 featured Glock's stock barrel which I personally considered unsafe for use of true 10mm full-power cartridges due to scanty case head support. This was a kaboom waiting to happen IMO. This was during the "draught" years when very few people were making 10's; or all the 10's out there were really watered down to .40 sw power (much ammo still is).
 
I have had no issues shooting .40 in my 10mm Glock 20.
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The only reason I wouldn't do it is because I've had a squib before in regular 10mm, fortunately the bullet stopped just in front of the chamber not allowing the next cartridge to go into battery. I could imagine a scenario where the shorter case of a 40 might not do that (possibly allowing the next cartridge to go into battery)--but that's conjecture on my part.
 
I bought a S&W 1006 back when there were police surplus versions around…back when law enforcement abandoned 10mm. So, before 10mm is as easy to get today. Sometimes, I found Silvertip or Blazer, but not a lot.
Saw a gun magazine article discussing using .40 in the 1006, I believe by Ed Sanow.
So, I gave it a try. My LGS sold Federal Classic .40 JHP’s pretty cheap. I found those to shoot great in the 1006, never an issue feeding or ejecting, and good accuracy.
As for the Glock 20, I know over at Glock forum, the G20, G29 guys talk about doing it a lot.
 
stagpanther: My first 20 featured Glock's stock barrel which I personally considered unsafe for use of true 10mm full-power cartridges due to scanty case head support.
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So, did you switch out the barrel? If so, to what and how hard was it to do, that is any hand fitting or was it a drop in conversion? Note: I would assume the new barrel would get rid of the 'Glock bulge' too.

That said, I really can't think the stock Glock 10mm is dangerous or they'd have been sued into oblivion by now. Just my opinion.
 
Pre-plandemic, I bought a police surplus Gen4 G22 with night sights in near 99% new condition for less than what a BarSto barrel would probably cost, lol.
 
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