View Full Version : Glock 21 convert to 10mm?

May 14, 2012, 04:19
I'm new to the Glock. Has anyone any experience/knowledge about converting the .45 21 to 10 mm by changing the barrel and magazines? What about changing out the recoil spring and guide? The .45 is plenty for most situations, but the 10mm would be a better woods gun in black bear country (augmented by a rifle or 12 ga with slugs).
So what do you know about converting the 21 to 20 given the correct parts? Thanks, Dun

May 14, 2012, 07:04
Six pages of discussion at http://glocktalk.com/forums/showthread.php?t=938598

May 14, 2012, 09:12
For what you will spend in time effort and parts... just buy a 10mm. I have been down this road. YMMV, but mine was not worth the time and effort.

May 14, 2012, 09:53
I dunno from Glocks; but.......

I'd sooner go the other way...20 to 21. The "woods" gun yer seeking would need some *real* 10mm ammo to provide the protection ya want. Not sure I'd trust an upward converted Glock ta deal with that kind pressure and recoil. With the available "FBI lite" loads out there... no worries; but something to discourage bear and such??

Balancing a high-intensity round like the full-house 10mm is more than changing springs...IMHO Mebbe Glock uses the same frame and details....mebbe they don't !?!?
Like Skilter sez... just buy a 10mm...or a short 12 ga. ;)

May 14, 2012, 17:46
Good info >> http://www.the-armory.com/shopsite_sc/store/html/product1057.html

I recomend the compensated model.

May 14, 2012, 22:13
I'm pretty sure the frames are the same size, but the 20's slide is larger than the 21. It has more weight to it, for a dampening affect I'm sure.

May 15, 2012, 04:58
Thanks for the info... I had wondered if switchy-swappy would work for the Glock- someone suggested that it would- like it does with the 1911.. sounds like NOT. Anyway I got what I wanted, a Glock in a large caliber that I can reload for- given, as I understand- an aftermarket bbl is used. Meanwhile I got lotsa hardball available. So far I like what Im getting from this Tupperware Toy- other than not able to reload for it. No desire to be left holding an expensive hand-grenade.
Do these things work with factory hollow-points? What exactly is the problem with reloads made to factory spec?

May 19, 2012, 16:26
The problem with reloading Glocks and lead bullets is the powder selected.

Everyone wants to use small charges of fast burning powders, to obtain maximum charges per pound.

Fast burning powders reach maximum temperature very quickly and vaporize the rear of the bullet. This vaporized lead is deposited around the throat of the barrel. This deposit creates added pressures because of the added obstruction.

If you use slow powders(Blue Dot) the max temp is reached 2/3 to 3/4 of the way down the barrel. No increase in pressures. Shooting a jacketed bullet removes the lead.

I have fired tens of thousands of rounds through Glocks with lead reloads with Blue Dot powder. Yes, it is dirty and does not always burn the whole charge.

Now, we have all seen revolvers turned into hand grenades.

That is caused by the other problem I have with fast powders. DOUBLE CHARGES!

Take a .357 case or a 45 auto case and drop a moderate charge of Bullseye.

Now drop another. It doesn't look much different, does it?

Now drop a moderate charge of Blue Dot, double it, clean up the mess from the powder spilling out of the case. There is no pistol case large enough to throw a double charge of Blue Dot.

40 years reloading, zero blown up guns. Ten fingers, 2 eyes, 2 ears.....

Cost is relative.

Check several Reloading Manuals before starting to work up loads. Hornady Seventh Edition Manual has very few Bullseye loads and several loads for slower (shotgun) powders in pistols. I think they are catching on.
Blown up guns= lawsuits= not economical for anyone


May 19, 2012, 21:45
The frames on the Glock 20 and 21 are the same. I have had a couple of G21s and currently have one G20 with an extra G21 slide and barrel. Finding a spare slide and barrel can be a bit of a challenge, but they are out there. They interchange fine, but i do use different recoil springs. I use the factory standard with the G21 and a Wolff guide rod and 22# spring with the G20. My G20 has digested somewhere in the neighborhood of 6K full power loads (factory and reloads) without a hiccup.

It makes a great woods pistol, especially with 200 grain WFNGC bullets. Mine feeds hollow points with no problems. I have found the G20 to be the most comfortable 10mm to shoot compared to the others I have owned and since sold (Colt Delta Elite, Dan Wesson PM7-10, S&W 1006, 1026, 1066, 1076, Glock 29).

May 19, 2012, 22:57
WFNGC bullets
What do the initials mean? Google didnt find them. Thanks, Dun

May 20, 2012, 09:00
wide flat nose gas checked

These are an example: