Another Glock conversion ?. .40S&W in a G20


March 4, 2008, 12:43 PM
Being a confirmed brass whore I never let the fact that I didn't have a .40S&W keep me from picking up that brass. When I hit critical mass I prepped the brass and am ready to load it. I worked up a load with my Smith 610 and am ready to try and add to my Glock20 to shoot .40S&W in it.

Conversion barrel. No problem, there are any number out there.


Will the regular 15 round G20 10mm mags work? If not, what type/capacity is required?



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March 4, 2008, 01:11 PM
Good question, because of the longer length of the 10mm...there may be some slack in the magazine.

Wouldn't a G27-23-22-35 mags fit into the G20 frame?

March 4, 2008, 01:59 PM
Well, I know for a fact the G22/15round won't. Or actually, it will. Loosey goosey.

I'm looking for some "real world" experience. I don't have the barrel yet, or I'd reload some in my G20 mags and cycle them (or shoot them!). I'm going to order some mags if the G20 15 round mags won't work with the shorter .40S&W ammo.

March 4, 2008, 02:27 PM
I owned a G-20 for a couple of years. Now that I'm a handloader, I wish I had it back.
I bought a KKM .40s&w conversion barrel and it was great. No problems at all. You use the standard 10mm magazines and recoil spring. I found that the .40 would even cycle the pistol with a 20 pound recoil spring (T.H.E. tungsten guide rod w/ISMI springs). Accuracy was outstanding. The best groups I ever shot with the .40s&w caliber were with the G-20 conversion.

.357sig conversions work the same way, I just never owned one.

Also in a pinch (read emergency), .40s&w rounds can be fired in the 10mm barrel. I shot 20 rounds of .40 ammo in my 10mm barrel just to see if it worked. It did. Most agree that it is hard on the extractor, but it does work.

The only trouble I ever had with the G-20 was with the then new full capcity magazines. I would get a few feed failures with both the .40 and 10mm barrels. 10 round mags were always flawless with either barrel.

I think the conversion barrel paid for itself in the price difference in ammo. If I get another G-20, I will definatly buy another .40 barrel.

March 4, 2008, 03:23 PM
Thanks, Hammer. That's encouraging. I was planning on four mags for the .40S&W. With shipping that's half the cost of a barrel or more, depending on the brand.

The best group I got was with 5 grains of Clays/WSP primers. Started out @ 3.4 and you could see the groups tighten as the powder increased. 5 grains is max in the Sierra manual, but the primers looked fine and I think in the S&W 610 I could increase a bit more, but I'll chronograph the load in my G20 @5 grains first. 5 grains in a Glock will be more reactive than the 610, if I have to guess. My groups were oatmeal cookie size and I was kneeling at a concrete bench and concentrating on not shooting my chrony!

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