Glock 21 10mm Conversion: Review & How To

[plouffedaddy]

http://i96.photobucket.com/albums/l178/tiffani33/Guns/IMAG1031.jpg

It seems like every week there's a question about how to do a 10mm conversion on a G21 or G30 (process is basically the same as below...). So I decided to do a little video explaining how to do it and demonstrate the difference in firepower you'll achieve while doing so.

Gun:
Generation 3 Glock 21SF with 1913 rail
Parts used for the conversion:
-KKM 6'' 45-10mm conversion barrel
-LWD 10mm extractor (KKM recomends modifying a stock 45acp extractor however; more on this in the video below)
-LWD stainless guide rod with 20lb recoil spring (vs 17lb factory set up)

Here's a video that will show how the gun shoots with the standard set up, 10mm conversion setup (with multiple types of ammo), a demonstration showing how to install the conversion parts, and chronograph tests with both setups of the gun showing the power difference with the 6'' KKM barrel.

G21 10mm Conversion Reveiw And How To Video Link (http://www.youtube.com/watch?v=Dt8s8d3RI4U&feature=g-upl)

Chrono data for the 45ACP:
-Federal HST 230gr JHPs: 817fps, 341 ft/lbs
-Winchester Ranger 230gr JHPs: 896fps, 410 ft/lbs

Chrono data for the 10mm:
-Underwood 155gr Gold Dot JHPs: 1587fps, 866 ft/lbs energy
-Blazer 200gr TMJ: 1098fps, 535 ft/lbs energy

[Matman87]

Solid info. I setup a Glock 23 in 9mm using the Lone Wolf 40-9 conversion barrel and some G-19 mags. I initially had no issues, but as things wore more the reliability began to get more sketchy. I would like to do this conversion to my 21 once I can reload ammo a bit easier then I can now.

Thanks for all the info!

[R0N]

I did this for a while, than got a 20, but than got a 40 cal barrel for the 20 and seem to shoot 40 cal more these days than either 10mm or 45.

[plouffedaddy]

Solid info. I setup a Glock 23 in 9mm using the Lone Wolf 40-9 conversion barrel and some G-19 mags. I initially had no issues, but as things wore more the reliability began to get more sketchy. I would like to do this conversion to my 21 once I can reload ammo a bit easier then I can now.

Thanks for all the info!

You're quite welcome.


I did this for a while, than got a 20

I love my Gen4 20 as well. It's out getting fitted for a threaded 6'' barrel as I write this :D
http://i96.photobucket.com/albums/l178/tiffani33/Guns/IMAG1257.jpg

[GJM]

I am in Northern Alaska with limited Internet, but was told that 10 in a 45 Glock was a no no, as the 10mm slide is heavier than the 45 slide to withstand the pressure of full power 10mm loads? As I recall, but can't access here, the factory specs show the 20 as a few ounces heavier than the 21, presumably in the slide?

[plouffedaddy]

I am in Northern Alaska with limited Internet, but was told that 10 in a 45 Glock was a no no, as the 10mm slide is heavier than the 45 slide to withstand the pressure of full power 10mm loads? As I recall, but can't access here, the factory specs show the 20 as a few ounces heavier than the 21, presumably in the slide?

You are correct---the milling on the slide is slightly different on the 20 vs the 21. That said, there are a lot of people out there running this conversion---I wouldn't hesitate to do it if I was you. Underwood ammo is pretty hot and I've ran a ton of it through my 21 with no issues. If I was up in AK and needed a little more power than the 45acp, I'd pick up a barrel and a magazine for sure.

[Rayrevolver]

Based on smart people at the GlockTalk 10 Ring Forum I went to a 22# (or maybe 24#, can't remember) spring for the G20. No issues with reliability for me.

With a lighter G21 slide, wouldn't you need more spring than a 20#?

[arushus]

I recommend a 24lb spring, especially if it is ISMI. I run a 22lb ISMI spring in my G20sf, and I notice very little difference between it and the stock spring..

[SW-Shooter]

You are correct---the milling on the slide is slightly different on the 20 vs the 21. That said, there are a lot of people out there running this conversion---I wouldn't hesitate to do it if I was you. Underwood ammo is pretty hot and I've ran a ton of it through my 21 with no issues. If I was up in AK and needed a little more power than the 45acp, I'd pick up a barrel and a magazine for sure.


The only difference between the two is the unloaded weight and different barrels, and magazine. The size: height, width, length, etc are all the same. The weight is about an ounce more in the G20 - 27.69 oz, G21 - 26.46 oz. I wonder if it's the barrel that adds the weight because it's hexagonal vs. octagonal. It could be the added length of the magazine because of the 2 round extra capacity as well. It you hold the two side by side you cannot see any difference.

[Rayrevolver]

The only difference between the two is the unloaded weight and different barrels, and magazine. The size: height, width, length, etc are all the same. The weight is about an ounce more in the G20 - 27.69 oz, G21 - 26.46 oz. I wonder if it's the barrel that adds the weight because it's hexagonal vs. octagonal. It could be the added length of the magazine because of the 2 round extra capacity as well. It you hold the two side by side you cannot see any difference.

I got this!!!

Took a weight watchers food scale (claims ~.1oz accuracy) and did some weighing. I did multiple weighs, multiple tares, on/off, but the scale said the same thing every time for each item. I don't know enough about scales to know if that means it is not very sensitive.


Gen3 G21SF slide, GNS, barrel, and recoil spring 21.00oz
Gen2 G20 slide, Ameriglo sights, and recoil spring 22.40oz
Gen3 G34 slide, Trij HD sights, and recoil spring 17.90oz

G21SF barrel only 4.0oz
G20 barrel only 4.65oz

If you look inside the slides are different but its very subtle. The G21 has more material removed along the interior walls towards the front sight.

[plouffedaddy]

Correct. It's slight, but it's there.

[arushus]

Plouffedaddy! Didnt think Id see you here...do you remember me from the 10-ring over on glocktalk? Just out of curiosity what kind of AR/M4 setup do you have? I just got myself a spikes tactical m4 carbine.