Glock 20 Gen 4

Why would you buy a 10mm and feed it 40 short and weak.
I think it will do it but I wouldn't bother wasting your time. If you want to shoot 40 buy a 40 and if you want a 10mm then buy a 10mm. I'm not sure how safe it is but I think I've read somewhere that some guys have done it. I wouldn't do it personally.
It's not the same as 357 and 38 in a revolver.

If you don't handload then the 10mm is a waste of money. Factory loads are weak like 40S&W, are harder to find and cost more.
 
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I have a Gen 3 and only use .40 when I have a .40 barrel installed. I don't know what would be different about a Gen 4 in that respect. I am super cautious to avoid shooting the wrong ammo in mine. I wouldn't think you would get consistent results even if it did work. Maybe you did mean using a .40 barrel.
 
B said:
People do it all over and without incident both with and without a .40 SW chambered barrel...
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Huh. Since they headspace on the mouth of the cartridge, I am surpirsed the firing pin reaches the primer. I'll have to compare dropping a .40 round into the 10mm barrel. Still no need for me to shoot it since I have the Lone Wolf .40 barrel. Been dragging my butt on getting a .357 SIG barrel for it too. Variety is fun.
 
KeltecFan said:
Huh. Since they headspace on the mouth of the cartridge, I am surpirsed the firing pin reaches the primer. I'll have to compare dropping a .40 round into the 10mm barrel. Still no need for me to shoot it since I have the Lone Wolf .40 barrel. Been dragging my butt on getting a .357 SIG barrel for it too. Variety is fun.
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The bullet headspaces on the extractor, when using .40 in a 10mm barrel.
 
Thanks for the feedback guys. I believe it head spaces on the extractor but wanted some other opinions.
 
The cartridge is held in place by the extractor in the case of a 10mm auto chamber. There are plenty of YouTube videos showing that it works reliably. The safety aspect is debatable but if I was in a pinch I'd feel fine doing it. Fortunately I can afford a proper barrel for when I want to get in some cheap practice.
 
I have a G20 gen 4 and feed it mostly .40S&W. Same mags for both calibers too. Not a single issue with feeding.

I bought a Wolf conversion barrel for it, and found it easier to practice with cheaper .40S&W than with more expensive 10mm.

When my 10mm brass arrived, I began reloading for it so it doesn't make much of a difference cost wise now, but I still shoot mostly .40 out of it other than when I'm getting ready for a wilderness trip to the US. That's when I'll swap out the barrel back to a 10mm and become reacquainted with that cartridge for carry on my trip.
 
no issues shooting 40 in a 10 mm glock, other then you may need a lighter recoil spring for some loads. Any production auto effectively headspaces on the extractor. There is no saftey issue, but if you shoot a pile of cast bullets you may need to clean the chamber well for reliable feeding with 10 mm again.
 
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