Glock 40: Shooting .40 out of a G40

D

Darker Loaf

New member
So, it has recently come to my attention that a G20's can be used, safely, to fire .40 S&W. Do G40's have the same slide weight and return spring that a G20 does? Will the differences of a G40 vs. a G20 mean less reliable function with .40 S&W instead of the proper 10mm? Does anybody own a G40?
 
It can be done with a conversion barrel. I don't know of anyone making a conversion barrel for the G40 just yet though. I'm sure LWD will soon enough.

I had the LWD 10mm > 40 barrel for my G20. Worked very well. Never a failure with it.
 
I want one! Heh, that'd be sweet if they had that new sniper gray color you just got. I'm sure they won't for the G40, though.
 
Are you asking about 40 cal out of stock 10mm barrel?

Actually, I've seen a fairly well watched youtube person state he shoots 40 cal out of a stock 10 mm barrel all the time. I bet we've even had a thread on that somewhere. Lots of responses about what can go wrong.

I probably wouldn't do it.

1) it could be similar to the 38's in a 357 all the time without cleaning and then when you go to chamber a 10mm round, you've got all this crud mucking up the shoulder to the chamber. Might not be able to chamber a full sized 10 mm unless you clean.

2) the shoulder isn't usually exposed to all the blow-by and heat but now you have the contents of a 40 cal case rushing past the shoulder. Could it wear/blunt the shoulder? Maybe.

3) The case is held on by a single extractor's tension only. More wiggle room front and aft could potentially allow the primer to back out and jam the gun. Or if the case slips the extractor on its way forward, it will be propelled back before the striker retracts and pierce the primer damaging the breech face.
 
Over the years I've seen enough posts of people doing it successfully to give it a try. I can report that at least in my G-20 the rounds feed, fire and eject perfectly. There is no difference in POI and at least with the limited sample I've tried my gun is more accurate with the 40's I've fired through it than the 10mm ammo.

Long term I can't say, I've fired enough (about 100 rounds) to satisfy myself it'd work in an emergency. I don't plan on doing it all the time, but I've read claims on various gun forums of folks firing thousands of rounds successfully.
 
Thanks for the feedback! I've heard a number of people on TFL claim that a 10mm can function well with .40.

For me, it is no issue that .40 S&W might not be adequate out of 10mm platform for self-defense, in terms of reliability. I'd stick with 10mm for self-defense and hunting, but having the .40 for plinking... that's gold. .40 is second only to 9mm for cheapness. I'd have my cake and eat it, too!

(For me having cheap plinking ammo is just a must for any gun.)
 
Well if you do it, be sure to keep us posted! Maybe wear gloves for the first few mags?

As a side note, is a Glock in 10mm different in grip dimensions from 40 cal?
I might eventually get a 10mm except it looks like it would REALLY be a pain to separate cases from 40 cal when I reload.
 
Lonewolf already makes a 6" G-20 to .40 conversion barrel. I've shot thousands of .40 in my G-20's for years. Vid bellow. .40 brass is cheap, 10mm brass is not, it's a no brainier.

 
Well then Dan-O and Darker Loaf,

Here's an idea.

If someone were to reload 40 S&W, could they purchase a 10mm pistol, a conversion barrel, and simply reload some very hot rounds closer to if not equivalent to 10mm?

This is partially a reloading question I know, but it's just an idea. If 10mm brass is expensive.... perhaps try to attain 10mm performance with a 40 casing. I wonder if powders like Bullseye would be up to the task. Dangerous if not carefully labelled and tried in another pistol.

Any ideas? Not like I'd actually try it since not in the market for 10mm right now.
 
I am no expert. I don't know that much about reloading, but I know that the .40 case was made because they realized that the larger 10mm case wasn't necessary to achieve the weak loads the FBI ended up settling on. If you look at ft/lbs of .40 cartridges and low-end 10mm--they are the same. So, "yes," but high-end 10mm will always beat high-end .40.
 
I've loaded .40 cases to 10mm OAL's and had good results.....

I would never even think about loading 10mm charges in a .40 case to .40 OAL. I like my fingers and my guns way too much.
 
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