10mm to .40 conversion barrel recommendation

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Ocraknife

New member
I'm looking at a Glock 20 but 10mm is very expensive around here. I'm considering buying a .40 replacement barrel so I can shoot it more economically on occasion. I'll still shoot 10mm I just want less expensive ammo too.

Is Lone Wolf a good choice?
 
I had a LW barrel for a Glock 45 in the past. I had great luck with mine, but it wasn't a conversion barrel. They are great to work with and I wouldn't hesitate to buy any of their products.
 
Just don't even bother with the conversion barrel. Ive shot thousands of cast .40 rounds through my aftermarket 10mm barrel. Shooting .40 from a glock 20 is very pleasant.

Double click the following picture for a vid of me shooting .40 from my G-20 longslide with a Stormlake barrel in it.

 
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Not thousands of rounds, but I've also used 40's through factory G20 and G29 barrels. Feed and function just fine, accuracy and POI are exactly the same.

I don't know about other gun brands, or how it will hold up long term. I was experimenting to see how well it worked. I've read multiple posts from others who do it regularly. In my case I was just interested to see if it were possible and could it be used in an emergency.
 
The practice of shooting .40 S&W in a 10mm chamber seems a little risky to me. If the round isn't captured by the extractor on the way up, it can fall forward in the chamber with the base unsupported.

This situation occurred on occasion in the 9mm Largo Astra 400s years ago, when the importers wrongly advertised them as being capable of shooting 9mm Luger, .380., 9mm Browning Long, etc. If the round wasn't captured by the extractor, and the firing pin was just long enough to detonate one of the shorter cartridges, you could end up with a blown case and subsequent damage to the gun and possibly the shooter.

You are relying on the Glock's ability to hold the .40 against the breech face with the extractor as it feeds. If one of them should ever slip ahead of the extractor, you have a potential problem.

Just sayin'

As always, YMMV.
 
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It's good to know that I could shoot .40 in a pinch out of the G20 but I think I might err on the side of caution and get a .40 aftermarket barrel anyway.

Are there any other barrels I should consider besides Lone Wolf?

Thanks.

Okra
 
In theory and practice, shooting the .40 round out of a 10mm barrel would work -- and I've done it myself with a S&W 1076. I just didn't do it much.

The problem is that the 10mm round headspaces on a lip in the chamber and the .40 case doesn't reach that far. You're relying on the extractor to keep things properly positioned.

What you could get, over time, is the same sort of build up in the barrel that you see in .357 barrels where a lot of .38 special is used -- nothing you can't live with or clean out, but it may make a later potential buyer wonder about what you've been doing with your gun.

Buying a second barrel isn't going to be that costly, and you can probably recover that cost by resale, or offering it with the gun itself, if it ever comes to that -- and in the meantime you have the option to use either.
 
Lone Wolf...they built my 9" barrel for my G20-SF.
Least expensive, very durable, fast turn-around on orders.
They even list next to each barrel if in stock or not,
and how long if out...

Walt Sherrill is spot on.
 
In October 2014 I went out into the sage brush 900 miles from home with a Glock 20 and a KKM 40sw conversion barrel. The stock spring averages 13 pounds over it's operating range. I made a recoil spring assembly that averages 22 pounds.
The KKM has chamber support from 0.200" and forward, while 40sw cases have a 0.180" thick web. This was a great set up.
I started to work up with Power Pistol and 200 gr Nos JHP 1.29" OAL.

I had a case failure at power levels a 10mm could attain.
But the 40 is a much stronger case and should do better.

I forget to throat the barrel for the wide bullets seated long.

I had no lathe out in the desert, so I gave up.
 
You're relying on the extractor to keep things properly positioned.
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Correct. That's not recommended for two reasons. It's hard on the extractor and, as pointed out, it can result in the case slipping past the extractor and causing excessive headspace.

Some testing showing the possible results can be found in the link below.
http://www.thegunzone.com/10v40.html

What you could get, over time, is the same sort of build up in the barrel that you see in .357 barrels where a lot of .38 special is used -- nothing you can't live with or clean out, but it may make a later potential buyer wonder about what you've been doing with your gun.
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There is another situation that could possibly arise.

Autopistol chambers are VERY different from revolver chambers. A revolver chamber generally has a very gradual taper at the front of the chamber while an autopistol chamber has an abrupt step at the front of the chamber.

Normally, the case mouth is against that step and so the bullet never makes contact with it.

When a shorter cartridge is fired through an autopistol chamber, it has to pass the step. The step can shave off bullet material which can build up over time. A sufficient amount of buildup can cause a partial obstruction and blow the gun.

If I were in a life-threatening situation and all I had was some .40S&W and a 10mm pistol, I wouldn't have a problem loading up and defending myself. But I wouldn't make a practice of it. It's not like it's an instant recipe for a catastrophe, but it does increase the potential for an unpleasant incident.
 
I had KKM .40 conversion barrels for a 20 and a 29, very accurate and 100% reliable.
G-291.jpg
 
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