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

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/

Quote from: DM1906 on August 20 2015 11:49:42 AM MDT
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/

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?

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.

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?

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?