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I've just ordered a KKM 40 S&W Conversion Barrel for my Glock 29. Age and a bit of arthritis have made 10mm somewhat unpleasant. I know it possible (but not ideal) to shoot .40 S&W from the 10mm OEM barrel and that underpowered 10mm loadings are possible. I choose to not use those options and instead opted for the KKM conversion barrel. I have no desire to purchase a 22 or 23 as the 29 fits me perfectly. My questions are:

Has anyone here done this type of conversion with his or her Glock 29? And what are your opinions of this new setup?
 

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I've just ordered a KKM 40 S&W Conversion Barrel for my Glock 29. Age and a bit of arthritis have made 10mm somewhat unpleasant. I know it possible (but not ideal) to shoot .40 S&W from the 10mm OEM barrel and that underpowered 10mm loadings are possible. I choose to not use those options and instead opted for the KKM conversion barrel. I have no desire to purchase a 22 or 23 as the 29 fits me perfectly. My questions are:

Has anyone here done this type of conversion with his or her Glock 29? And what are your opinions of this new setup?
I have done it, in fact, with a KKM 40 conversion barrel. It worked flawlessly out of the box. I finally stop bothering with the KKM barrel as 40's shoot fine from my stock G29 and G20 barrels.

I ultimately sold my KKM barrel as it never made it out of the bag.

Anyone who tells you there is a single deleterious effect from shooting 40's from your G29/G20 guns, is talking from flawed theory, versus actual fact.

But if it makes you feel better, the KKM conversion barrel should work without a hitch.

PS - 40 from a G29/G20 is absolutely joyful.
 

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WeeWilly, do you have sticky extraction if you go back to 10mm without a good chamber scrubbing? Used to happen to my 357 after a bunch of 38 rounds.
You know, I don’t know as I always clean my guns after shooting them (old habits die hard).

I suspect you might as the fouling is likely very similar. A chamber brush and some CLP seems to eliminate any issues. I have 10’s of K rounds of 40 cased ammo through my G29’s and G20’s (I even load my plinking 10mm rounds using 40 cases, to 10mm OALs of course), never a hitch.
 

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With my 357 I used 38 and 357 at same session so that's why it caused me sticky extraction. Especially smoky lead cast bullets. I quit doing that.
I will test it one of these days. I have a bunch of 40 cased 175gr LSWC loaded up (unfortunately coated, so not exactly apples to apples), I will run a couple hundred through and then try some of my 200gr WFNGC loads I use for trail carry. I would be willing to bet, in the generous Glock chamber, it works fine.

PS- if you are going to swap barrels to swap calibers, you are going to field strip it any way. A brush and then patch isn’t going to be a great deal more work. But I bet it works fine dirty.
 

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I have the KKM barrel also in .40 for my 29.
Practice more now I have a less expensive option.
I also have the .357 Sig for my 20 and 29. Really like the round.
Before joining the forum I didn’t shoot .40 in my 10mm.

You should do fine, I have fired well over 5,000 rounds with the conversions.
 

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I have a storm lake conversion barrel in my G20. I would have bough a KKM but thr SL was on the shelf at my LGS. It was a great investment. I reload but I want the ability to buy cheaper and more readily available factory ammo. The barrel works without a hickup and is every bit as accurate as the stock barrel. 10mm-40 S&W should be the most reliable conversion as the case head is the same size. I think you will enjoy thr KKM
 

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I bought a Lone Wolf .40 conversion barrel for my G29 and it has been flawless. I did have to send it back since the accuracy was sub-par and it was re-crowned and is now very impressive.

 
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Just because the extractor will usually hold the .40 S&W case to the rear of the breechface and effectively set headspacing via the extractor 999 times out of 1000 (or more) does not make it a good idea, save for perhaps some sort of a zombie apocalypse scenario, etc. Get the conversion barrel. (It is NOT the same as shooting .38 Specials out of a .357 Magnum, .44 Spl in a .44 Mag, etc., as those are rimmed cartridges, and headspace on the rim. With no ledge in chamber for case support, the cartridge *could* go a bit too far forward, and still ignite from primer hit, but allow the entire rear of the case and/or primer to blow out, and a case blowout down the magwell is bad news, especially if there is sympathetic detonation of one or more cartridges left in the magazine.)

I used a Lone Wolf .40 S&W conversion barrel in my Gen 3 Glock 20, and, although I did have to shorten OAL of my moly coated bullet handloads by a few thousandths dues to tighter chamber tolerances (from 1.14" to 1.12" with Precision RNFP bullets), it worked flawlessly.
 

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Just because the extractor will usually hold the .40 S&W case to the rear of the breechface and effectively set headspacing via the extractor 999 times out of 1000 (or more) does not make it a good idea, save for perhaps some sort of a zombie apocalypse scenario, etc. Get the conversion barrel. (It is NOT the same as shooting .38 Specials out of a .357 Magnum, .44 Spl in a .44 Mag, etc., as those are rimmed cartridges, and headspace on the rim. With no ledge in chamber for case support, the cartridge *could* go a bit too far forward, and still ignite from primer hit, but allow the entire rear of the case and/or primer to blow out, and a case blowout down the magwell is bad news, especially if there is sympathetic detonation of one or more cartridges left in the magazine.)

I used a Lone Wolf .40 S&W conversion barrel in my Gen 3 Glock 20, and, although I did have to shorten OAL of my moly coated bullet handloads by a few thousandths dues to tighter chamber tolerances (from 1.14" to 1.12" with Precision RNFP bullets), it worked flawlessly.
First, the lion's share of 10mm cartridges being fired from a Glock 10mm chamber is being head spaced by the extractor. The spring loaded extractor on the Glock does an excellent job of holding the case against the breech face. The reason they headspace like this is because ammo manufacturers (and case manufacturers like Starline) assure their cases are not to maximum SAAMI length as failure to go into battery would result with the slightest buildup of any debris at the end of the chamber. They are shorter than maximum on purpose.

Second, your supposition of what might happen if the case did get past the extractor (or say the extractor broke and the case slipped past) is in error as well. The Glock FP has a positive stop, such that it cannot reach the primer if a 40 case actually did get past the extractor (an almost zero possibility proposition.

You can check it yourself, simply field strip your Glock 10mm gun, insert a 40 cased round inside the chamber, ahead of the extractor. Now, depress the FP safety and slide the FP to its maximum reach. It will not reach the primer.

You see, technically speaking, the 10mm Glock doesn't know if it is shooting a 40 or a 10 cartridge, they function exactly the same from a practical standpoint in the gun. These are the facts as they stand.

I think it is fine if people want shoot their 40's out of their conversion barrel. I did that too until I figured out what is actually going on with the gun. But it does get tiring explaining it over and over to those that don't understand how the gun operates and why it is perfectly fine.
 

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First, the lion's share of 10mm cartridges being fired from a Glock 10mm chamber is being head spaced by the extractor. The spring loaded extractor on the Glock does an excellent job of holding the case against the breech face. The reason they headspace like this is because ammo manufacturers (and case manufacturers like Starline) assure their cases are not to maximum SAAMI length as failure to go into battery would result with the slightest buildup of any debris at the end of the chamber. They are shorter than maximum on purpose.

Second, your supposition of what might happen if the case did get past the extractor (or say the extractor broke and the case slipped past) is in error as well. The Glock FP has a positive stop, such that it cannot reach the primer if a 40 case actually did get past the extractor (an almost zero possibility proposition.

You can check it yourself, simply field strip your Glock 10mm gun, insert a 40 cased round inside the chamber, ahead of the extractor. Now, depress the FP safety and slide the FP to its maximum reach. It will not reach the primer.

You see, technically speaking, the 10mm Glock doesn't know if it is shooting a 40 or a 10 cartridge, they function exactly the same from a practical standpoint in the gun. These are the facts as they stand.

I think it is fine if people want shoot their 40's out of their conversion barrel. I did that too until I figured out what is actually going on with the gun. But it does get tiring explaining it over and over to those that don't understand how the gun operates and why it is perfectly fine.
This ^
 

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I have only ever had one problem with shooting 40 S&W out of my OEM Glock 20 and/or 29 barrels. I have had FTF (FT Fire) in both the 20 & 29 because the bullet went into the chamber ahead of the extractor. This allowed the firearm to go into battery with a live round in the chamber but with a gap between the base of the cartridge and the slide causing the firing pin to not be able to hit the primer; and if it did the round wouldn’t have ejected. These FTF’s occurred at a range and weren’t that big of deal, however because of this I would NEVER trust my life to one of my OEM barrels in 10mm shooting 40 S&W. If these FTF’s would have occurred in a self-defense situation the normal method of getting the firearm back into action would not work. In my experiences, I had to drop the mag, lock the slide back, and shake the gun with the muzzle pointed upward until the round fell out. Other than myself I have never seen anyone mention this as an issue.

All that being said I have 22 lbs recoil springs in the 20 and a 21 lbs in the 29 and with the exception of the above situation the weapon functions well and is a dream to shoot with 40 S&W.
 

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I have only ever had one problem with shooting 40 S&W out of my OEM Glock 20 and/or 29 barrels. I have had FTF (FT Fire) in both the 20 & 29 because the bullet went into the chamber ahead of the extractor. This allowed the firearm to go into battery with a live round in the chamber but with a gap between the base of the cartridge and the slide causing the firing pin to not be able to hit the primer; and if it did the round wouldn’t have ejected. These FTF’s occurred at a range and weren’t that big of deal, however because of this I would NEVER trust my life to one of my OEM barrels in 10mm shooting 40 S&W. If these FTF’s would have occurred in a self-defense situation the normal method of getting the firearm back into action would not work. In my experiences, I had to drop the mag, lock the slide back, and shake the gun with the muzzle pointed upward until the round fell out. Other than myself I have never seen anyone mention this as an issue.

All that being said I have 22 lbs recoil springs in the 20 and a 21 lbs in the 29 and with the exception of the above situation the weapon functions well and is a dream to shoot with 40 S&W.
That is a very puzzling experience. I am not doubting your experience, I just can't imagine how the round got fed into your gun ahead of the extractor?

I literally have loaded and shot tens of thousands of 40 cased ammo, both 40S&W loads and 10mm loads using 40S&W cases through my stock Glock 10mm guns and never had a misfeed as you describe.

As for your comment regarding using 40's in any 10mm gun for any kind of defensive application, or even hunting, I totally agree. When I say people can shoot 40's in their stock 10mm Glocks, I am talking about range/target style shooting. I use my G20 and G29 as my woods carry weapons and I carry 10mm cased 200gr WFNGC rounds for that application.

PS- While I usually mention this disclaimer when discussing 40 from 10mm Glocks, I may have missed it this time. 40 from a 10mm Glock is a Glock only proposition. 40 from a 10mm gun that doesn't have a positive firing pin stop (like a 1911 platform), is a bad idea for the rationale stated by Msgt Dotson. If the round did get ahead of where the extractor held it, say with a broken extractor, the firing pin could reach the primer and fire the round. This would likely result in a case head kaboom. A normal pressure case head kaboom is usually not the end of the world, with perhaps the magazine getting ejected and a puzzled shooter holding an unloaded gun, but still not something you would seek out for fun.
 

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I've just ordered a KKM 40 S&W Conversion Barrel for my Glock 29. Age and a bit of arthritis have made 10mm somewhat unpleasant. I know it possible (but not ideal) to shoot .40 S&W from the 10mm OEM barrel and that underpowered 10mm loadings are possible. I choose to not use those options and instead opted for the KKM conversion barrel. I have no desire to purchase a 22 or 23 as the 29 fits me perfectly. My questions are:

Has anyone here done this type of conversion with his or her Glock 29? And what are your opinions of this new setup?
Great topic. Was just thinking of getting a 40 conversion barrel for my G29.
Quick question?
Will a Glock 20 gen 4 oem barrel fit in a Glock 29 gen 4?


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I've just ordered a KKM 40 S&W Conversion Barrel for my Glock 29. Age and a bit of arthritis have made 10mm somewhat unpleasant. I know it possible (but not ideal) to shoot .40 S&W from the 10mm OEM barrel and that underpowered 10mm loadings are possible. I choose to not use those options and instead opted for the KKM conversion barrel. I have no desire to purchase a 22 or 23 as the 29 fits me perfectly. My questions are:

Has anyone here done this type of conversion with his or her Glock 29? And what are your opinions of this new setup?
I have an Alpha Wolf 40 S&W conversion barrel for my G20 works great. It certainly tamed the cartridge down.
Also have KKM 10MM BARREL AND COMPENSATOR for Glock 20. Both are good choices. Would recommend either or.

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Great topic. Was just thinking of getting a 40 conversion barrel for my G29.
Quick question?
Will a Glock 20 gen 4 oem barrel fit in a Glock 29 gen 4?


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I believe that it Will. Although you will have some extra barrel protruding out of the end of the slide, everything else should be exactly the same .
 
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