Shooting 40sw in a 10mm Glock

**batman69** · 15-05-2022, 19:01

Hi guys,

So I discovered something very interesting and totally new to me today.

You can shoot 40sw out of a 10mm Glock!

Totally legal as well.

Also gives one the option of having the best of both calibres. 40sw would be cheaper to shoot and practise with. 10mm would be ideal for carry.

Amazing.

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**KK20** · 16-05-2022, 00:19

Tell us more

**Skaaphaas** · 16-05-2022, 00:29

I suppose the extractor would hold the case in place, as it cannot effectively headspace off the case mouth. Depending on how much movement of the case the extractor allows, light strikes are a possibility. Pistol-dependent then, I think.

You’d have significant bullet jump to the lands but seeing as people shoot .38Spl in .357Mag revolvers it doesn’t seem to be a major issue.

**batman69** · 16-05-2022, 05:29

Thanks guys. I'm no expert on this at all.
I went to the range yesterday with a colleague who owns the G20. I did not find the recoil unmanageable with the 10mm rounds
(180g S&B).

The 40sw round was shorter when placed into the magazine. To be expected.

It chambered properly . The extractor worked and the slide locked back on the last round. No light primer strikes encountered in the 120 odd 40sw rounds fired but I accept that this might happen.

I'm wondering if there are any proven drawbacks to using the 40sw rounds in the G20, especially for continued long term use.

I don't think many can deny the proven ballistic capabilities of the 10mm. The main disadvantages mentioned is the harsh recoil, cost and availability of ammo. The recoil is really not harsh at all. With the correct grip and frame of mind the recoil issue is relative.

If one can safely shoot 40sw ammo through the gun, this mitigates the cost and availability of 10mm ammo issue because the gun will not become the proverbial safe queen. One can then source 10mm as and when there is availability and budget accordingly without the need to sell the gun due to a lack of use.

Perhaps the sweet spot for an edc option is the G29, with a G20 mag as back up.

Decisions, decisions.... :)

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**Cockroach** · 16-05-2022, 06:41

Define "Chambers properly"?

The .40 is meant to headspace on the case rim. It cannot properly do that in a 10mm chamber

Kinda like 9x19 and 9 x 17

**mckg** · 16-05-2022, 07:00

Quite a few shooters brag about doing it. Like shooting smokeless powder in Blackpowder guns. Nobody I know of has come forward confessing that after all it was a very bad idea. I say extractors are not engineered for the job. Would it be legit to use a 40 barrel in that gun?

**Adoons** · 16-05-2022, 07:25

My 2 cents. If cost of 10 mm vs 40 sw is the issue, start reloading for the 10 mm.

**Ds J** · 16-05-2022, 07:37

Batman, I would not do it.

From wikipedia:

" The .40 S&W case length and overall cartridge length are shortened, but other dimensions except case web and wall thickness remain identical to the 10mm Auto. Both cartridges headspace on the mouth of the case. Thus in a semi-auto they are not interchangeable. Fired from a 10mm semi-auto, the .40 Smith & Wesson cartridge will headspace on the extractor and the bullet will jump a 0.142 inches (3.6 mm) freebore just like a .38 Special fired from a .357 Magnum revolver. If the cartridge is not held by the extractor, the chances for a ruptured primer are great.[9] "

**batman69** · 16-05-2022, 09:29

Originally Posted by Ds J

Batman, I would not do it.

From wikipedia:

" The .40 S&W case length and overall cartridge length are shortened, but other dimensions except case web and wall thickness remain identical to the 10mm Auto. Both cartridges headspace on the mouth of the case. Thus in a semi-auto they are not interchangeable. Fired from a 10mm semi-auto, the .40 Smith & Wesson cartridge will headspace on the extractor and the bullet will jump a 0.142 inches (3.6 mm) freebore just like a .38 Special fired from a .357 Magnum revolver. If the cartridge is not held by the extractor, the chances for a ruptured primer are great.[9] "

Hi Ds J,

The bullet jump issue seems a neutral factor based on the same phenomenon present when shooting 38spl out of 357 magnum.

The more concerning issue is the round head spacing on the ejector i.e. the reliability of the ejector holding the round in place. Reliability will probably be dependant on the specific pistol and platform. I don't think anyone has specifically researched the long term reliability of the G20, for instance.

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