10mm pistols, 40cal ammo

[Edge]

Who has shot .40cal thru a pistol chambered for 10mm? Step forward, testify. If you haven't, spare forum readers the .40 is the wrong ammo quips, we'll just assume thats obvious. However Google the subject and you'll find thread after thread dealing with the subject.

[Suck My Glock]

I've done it, in a G20. Bought the wrong ammo by accident a number of years ago and didn't realize it til I got to the desert. Disappointed in my lack of attention, and also not wanting to waste the time I had set aside, I decided to proceed anyway.

My idea was that I could carefully chamber a single round at a time and simply do some draw and fire drills. No need to fire strings of multiple rounds. I'd just make it a day of doing some simple fundamentals.

However, I noticed over the years that the G20 was sprung somewhat lightly, to enable using both low and mid-range loads, as well as the hot stuff. The elasticity under recoil of the polymer frame allowed for the slide velocity of the hot ammo to not beat the gun apart, as had been the case in the early Colt Delta Elites. And so, the Glock tended to eject rather reliably the lower power 10mm ammo that some guns would choke on. Feed reliability was the typical impressive Glockness. My curiosity to investigate sparked in my imagination.

I noticed the single .40 rounds were ejecting, although barely, and depositing at my feet. So I experimented to see if the short stubby rounds would feed from the magazine. I would stick only a single round in the mag, insert it, rack the slide,...and to my surprise, it would feed and chamber 95% of the time. Upon firing, the slide would lock back, indicating that the pistol might in fact both feed AND fire. So on a whim, I loaded a 10mm mag full of Winchester white box 180grn. FMJ .40 ammo to see if the stuff would actually work as I thought it might. I was amazed at the reliability with which it did so successfully! I burned through 3 boxes of .40 that day with only 2 feed hiccups, both of which just required a small retraction of the slide to the rear by a millimeter or so, then letting the slide go home to finish chambering the .40 ammo.

I carefully inspected spent casings and the gun itself for any signs of odd or out of the ordinary things. For whatever reason, the G20 was reliably piercing the primers. But other than that,...no signs of anything to be concerned. Accuracy was acceptable. And not having to chase brass was a nice touch.

I haven't bothered to do it since then. But it is nice to know that in a pinch, without a conversion barrel or anything, I could use .40 if nothing else was available.

[Edge]

I've done it, in a G20. Bought the wrong ammo by accident a number of years ago and didn't realize it til I got to the desert. Disappointed in my lack of attention, and also not wanting to waste the time I had set aside, I decided to proceed anyway.

My idea was that I could carefully chamber a single round at a time and simply do some draw and fire drills. No need to fire strings of multiple rounds. I'd just make it a day of doing some simple fundamentals.

However, I noticed over the years that the G20 was sprung somewhat lightly, to enable using both low and mid-range loads, as well as the hot stuff. The elasticity under recoil of the polymer frame allowed for the slide velocity of the hot ammo to not beat the gun apart, as had been the case in the early Colt Delta Elites. And so, the Glock tended to eject rather reliably the lower power 10mm ammo that some guns would choke on. Feed reliability was the typical impressive Glockness. My curiosity to investigate sparked in my imagination.

I noticed the single .40 rounds were ejecting, although barely, and depositing at my feet. So I experimented to see if the short stubby rounds would feed from the magazine. I would stick only a single round in the mag, insert it, rack the slide,...and to my surprise, it would feed and chamber 95% of the time. Upon firing, the slide would lock back, indicating that the pistol might in fact both feed AND fire. So on a whim, I loaded a 10mm mag full of Winchester white box 180grn. FMJ .40 ammo to see if the stuff would actually work as I thought it might. I was amazed at the reliability with which it did so successfully! I burned through 3 boxes of .40 that day with only 2 feed hiccups, both of which just required a small retraction of the slide to the rear by a millimeter or so, then letting the slide go home to finish chambering the .40 ammo.

I carefully inspected spent casings and the gun itself for any signs of odd or out of the ordinary things. For whatever reason, the G20 was reliably piercing the primers. But other than that,...no signs of anything to be concerned. Accuracy was acceptable. And not having to chase brass was a nice touch.

I haven't bothered to do it since then. But it is nice to know that in a pinch, without a conversion barrel or anything, I could use .40 if nothing else was available.

Did your G20 have the stock spring?

[Suck My Glock]

Yes, everything on my G20s have always been stock except for night sights and skateboard tape on the grips.

[was21]

Did it years ago in my para ordnance 10mm... runs just fine.
Have repeated it in several other platforms with only minor feed problems in a couple.
I quit trying to tell people that it works and have to listen to all the hand wringing and proclamations of instant death and dimemberment that would be caused by something that “ will not work”.... all the while standing there and watching the pistol chug along.

Of course I grew up drinking out of a hose....

Recommended.... probably not.
Doable.... yes
FWIW
YMMV

[Edge]

Lol

[mike400]

I shoot 40cal out of my Glock 40 mos. I got a Lone wolf .40 barrel and with no other changes including mags, its shoots 100%. Now I have heard you can shoot .40 with the 10mm barrel but I see no need to do that.

[bsonline]

I used to pick up 40 s&w dropped by police training at a range I used to shoot at in Oregon. They fired more or less reliably in my Smith & Wesson 1006. Until (after many rounds) the empties stopped extracting. Not headspaced properly the extractor was the only thing holding the round in place to be struck by the firing pin. The extractor eventually bend.

The bend extractor would no longer extract a 40cal. nor a 10mm case. Removing the extractor and hitting it with a hammer returned the gun to normal functioning. And returning the range find ammo to the range.

[nvgdude]

The idea that straight wall pistol cases headspace off the case mouth is more or less a myth. In most pistols, it headspaces off of the extractor.

It's reasonably common to hand-load extra-long .40 S&W for 10mm 1911s. Loading long improves feeding.