G21 to 10mm spring weight

[R.Kell628]

I'll be getting a G21 soon and want to convert it to 10mm. I was just going to get a G20 and was already planning on getting an aftermarket barrel so I figured I might as well have 2 in 1. I'll go with either a storm lake or kkm conversion barrel and modify the 45 extractor.  I'll be using full power Underwood loads to carry in the woods so I want to get a stainless guide rod and heavier recoil spring but I can't find a definite answer on a 20# or 22# spring. I don't plan on using any of the weaker loads so that shouldn't be an issue. Suggestions?

[The_Shadow]

Well I wouldn't use less than 20 lb but I run a wolff Non-Captive 22 lb spring in my G-20SF with the Wolff steel Guide rod

[R.Kell628]

Am I just being dense here? When buying new springs, does it with two? On the  lone wolf site, Wolff brand shows two but ISMI brand shows one. Glockmeister seems to only offer single springs without buying the whole assembly. How does this work?

[DM1906]

Am I just being dense here? When buying new springs, does it with two? On the  lone wolf site, Wolff brand shows two but ISMI brand shows one. Glockmeister seems to only offer single springs without buying the whole assembly. How does this work?

That model Wolff spring is a 2-piece, inner/outer (progressive weighting). They only offer it for models G19 and G30 (which is curious). They will "fit" the Gen3 G20/21, but won't be correctly weighted.

The ISMI and LWD springs are single, flat-wound springs. I use the ISMI springs with SS captive rods. I suggest a 22# spring with your G21 slide, and a 20# with a G20 slide (as Shadow suggests), for full power ammo (Underwood, BB, etc.). The spring difference just about offsets the mass difference of the two slides (the G21 is lighter). The stock Glock RSA (17#) is a bit light for the G21 slide and full power 10mm, but it functions fine. Off-the-shelf (weak name-brand) ammo won't make much difference, either way you do it. Even .40SW in either slide with either spring function fine. However, a 24# spring on the G20 slide won't lock back on the last .40, but will about 1/2 the time with the G21 slide.

Also, you shouldn't need to modify the extractor. It should work just fine, as is. If you have issues with it, you should just get a 10mm extractor and switch them when you switch the barrels. It only takes a minute.

[R.Kell628]

Thanks. So there are no spring sets available for a g20/21 gen 4 dual assembly? Is there any cons to going to a one piece stainless guide rod in a gen 4 vs the dual spring?

And I'll try the stock extractor first and see how it works.

[DM1906]

Thanks. So there are no spring sets available for a g20/21 gen 4 dual assembly? Is there any cons to going to a one piece stainless guide rod in a gen 4 vs the dual spring?

And I'll try the stock extractor first and see how it works.

Ok. You didn't specify Gen4, which changes things a bit. The slides are slightly lighter than previous gen's. LWD sells the Gen4 SS RSA, which easily accommodates spring weight changes. The Gen4 springs are a lot more forgiving, so I suggest trying the OEM before upgrading. If case ejection remains within your zip code, it's probably OK.

That said....
The dual spring brings in a more complicated system to upgrading as well. It is almost never necessary to upgrade both springs, and very small weight changes of the secondary spring has a much greater functional affect than single-spring RSA changes. Moving away from OEM spring weights can cause a pistol to be mission-specific. Meaning, if you accommodate full power ammo, it may not funciton reliably, or at all, with lighter, name-brand ammo.

Otherwise, Gen3 springs can be used on Gen4 pistols, but an adapter bushing is required. This works well, but changes your entire RSA approach.

[R.Kell628]

Sorry, I should have been more clear, I'm referring to all gen 4. So now I'm lost. I don't want to use the stock spring when converting the g21 to 10mm due to full power loads and the lighter slide weight in the g21. I've seen the gen 4 dual spring ss rods from lwd but they only come in stock weight. So where do I get the other weight Springs for the dual spring rod? Even if I only replace one spring?

[The_Shadow]

The gen 4 factory spring is good out of the box for most stuff, the gen 4 also has a larger purchase in the Slide where the spring sits...



To use the Wolff Spring they make a adapter button...



Then there was a retro fit for some models, but not for the 10mm guns if I recall

[DM1906]

Sorry, I should have been more clear, I'm referring to all gen 4. So now I'm lost. I don't want to use the stock spring when converting the g21 to 10mm due to full power loads and the lighter slide weight in the g21. I've seen the gen 4 dual spring ss rods from lwd but they only come in stock weight. So where do I get the other weight Springs for the dual spring rod? Even if I only replace one spring?

Try the OEM, first. If you find it's inadequate, get the LWD SS factory weight and try it (you'll need it anyway for future spring changes). If it's inadequate, then consider spring changes. Once you start down that road, you'll be deep in the weeds of the engineering. Simply changing one spring or the other is NOT as simple as changing the single spring of previous models. You need to evaluate the action and determine what, exactly, makes that RSA inadequate, and adjust only that spring. Using the LWD Gen4 RSA allows you to change spring weights, but that doesn't mean you should, and it certainly doesn't help with the spring weight selection.

Or, just use a Gen3 spring of the correct weight and properly set up to operate with your Gen4 slide and 10mm barrel. Simply, LWD SS rod, 20# ISMI spring, Gen4 adapter, and LWD 10mm barrel. This is what I have done, and it works 100%. You can mix/match brands, but it will likely affect the end result. The different barrel brands are timed differently, good or bad depends on other component selections.

[R.Kell628]

Try the OEM, first. If you find it's inadequate, get the LWD SS factory weight and try it (you'll need it anyway for future spring changes). If it's inadequate, then consider spring changes. Once you start down that road, you'll be deep in the weeds of the engineering. Simply changing one spring or the other is NOT as simple as changing the single spring of previous models. You need to evaluate the action and determine what, exactly, makes that RSA inadequate, and adjust only that spring. Using the LWD Gen4 RSA allows you to change spring weights, but that doesn't mean you should, and it certainly doesn't help with the spring weight selection.

Or, just use a Gen3 spring of the correct weight and properly set up to operate with your Gen4 slide and 10mm barrel. Simply, LWD SS rod, 20# ISMI spring, Gen4 adapter, and LWD 10mm barrel. This is what I have done, and it works 100%. You can mix/match brands, but it will likely affect the end result. The different barrel brands are timed differently, good or bad depends on other component selections.

Thanks, that is helpful. I see that glockmeister makes a single spring ss rod for the gen 4. Any advice on that?

http://www.glockmeister.com/Glockmeister-Stainless-Steel-Recoil-Spring-Assembly-for-Gen-4-G20-G21-and-G41/productinfo/G4SS20CS/

[R.Kell628]

And on their dual spring ss rod they say they only come in stock weight and to use the sing spring for a custom weight.
http://www.glockmeister.com/Glockmeister-Gen4-Dual-Captive-Stainless-Recoil-Assembly-for-GLOCK-20_21_41-Generation-4/productinfo/GMDCG420/

[DM1906]

Try the OEM, first. If you find it's inadequate, get the LWD SS factory weight and try it (you'll need it anyway for future spring changes). If it's inadequate, then consider spring changes. Once you start down that road, you'll be deep in the weeds of the engineering. Simply changing one spring or the other is NOT as simple as changing the single spring of previous models. You need to evaluate the action and determine what, exactly, makes that RSA inadequate, and adjust only that spring. Using the LWD Gen4 RSA allows you to change spring weights, but that doesn't mean you should, and it certainly doesn't help with the spring weight selection.

Or, just use a Gen3 spring of the correct weight and properly set up to operate with your Gen4 slide and 10mm barrel. Simply, LWD SS rod, 20# ISMI spring, Gen4 adapter, and LWD 10mm barrel. This is what I have done, and it works 100%. You can mix/match brands, but it will likely affect the end result. The different barrel brands are timed differently, good or bad depends on other component selections.

Thanks, that is helpful. I see that glockmeister makes a single spring ss rod for the gen 4. Any advice on that?

http://www.glockmeister.com/Glockmeister-Stainless-Steel-Recoil-Spring-Assembly-for-Gen-4-G20-G21-and-G41/productinfo/G4SS20CS/

Looks like a copy/clone of LWD's original Gen4 adapter spring. Probably OK with ISMI springs. I like Glockmeister products, generally, but I've not used this to approve or disapprove. The description doesn't specify the spring weights can be adjusted, only ordered in different weights. Unless you know exactly what you want, I wouldn't recommend this one. They don't accept returns for weight adjustments.

[DM1906]

And on their dual spring ss rod they say they only come in stock weight and to use the sing spring for a custom weight.
http://www.glockmeister.com/Glockmeister-Gen4-Dual-Captive-Stainless-Recoil-Assembly-for-GLOCK-20_21_41-Generation-4/productinfo/GMDCG420/

There's a reason they only offer this in OEM weight. Probably for all the reasons I described previously, too many variables to offer a universal RSA. Get your gun and shoot it. THEN decide if modification is needed/wanted. All of this may be moot at that point, anyhow.

[R.Kell628]

Glockmeister got back to me in email and said the single spring rod I listed is the one to get to change between different spring weights. I think I'll get that with either a 22 or 20 pound spring and leave the dual 17 pound for use with 45acp