Trying to read about Glock recoil springs... shit is making my head hurt.

I bought a G35.4 that I’m converting to 357 Sig, and I plan on running some pretty warm loads.  I’d like to try 20# and 22# springs to keep the frame from getting beat up.

I’ve ran other poundage springs just fine in a G34.3 that I have, but this one’s a gen 4, and I’d like to use a captive setup like stock, but just with a heavier spring.

Anybody make a gen 4 style RSA in heavier poundages?

Polymer frames flex and then return to original shape.   I’ve never seen a captured spring for a Gen 4 Glock with heavier weight springs advertised.   I suggest you just replace the factory 357 Sig captured recoil assembly every 2000 to 2500 rounds.  I doubt the hot loaded 357 will produce anymore recoil momentum than the 40 in a Glock 34/35.   Honestly I don’t think you’ll see a lot of on target difference trying to hot rod a 357 Sig.   Even in trying to knock over steel plates with the quickest time using a standard 357 and a hot 357 load I think accuracy is more important than 50-75 FPS in velocity.

This unless you are poking holes in some 4 legged critters no point in pushing the .357 load.  Also pushing the load beyond its envelope will make the bullets suffer as they are designed to expand in a certain window.

Thanks for the input guys.  Not running plates or matches, but will use on critters.  Going to be running a hot 65gr. load.  Going to do more tests on armor too.  My g32.4 already swiss cheeses 3a with the Underwood 65gr XD load, but I want to chase longer barrel velocities and work up some hand loads with that bullet.

I can’t find anything like the oem gen 4 dual spring setup that offers a heavier spring weight, so I’ll just try the factory one and change it more frequently if I don’t come across something else I fancy more.

You don't need it.  I ran a Gen4 RSA from a Glock 21 when I was playing with .45 Super, ran loads that made over 1000 ft-lbs and it did just fine.  I have a Gen4 23 and Gen4 35 and I promise you, no 357 SIG is going to be an issue.  I've ran 357 SIG handloads through them both when I was experimenting with running actual .357" bullets in the 357 SIG, ran a 125gr JHP to 1700, a 140gr JHP to about 1550 and a 158gr JHP to 1400 (6" KKM barrel) and no issues.  The .40 recoils harder, I've ran 135's to 1850 and 200's to around 1300 fps (6" KKM), no issues.    If this were Gen3 then yes, you would need heavier, but Gen4 recoil assembly is good to go for hot stuff.

If you decide you need one, NDZ performance makes gen 4 specific guide rods with heavier springs.

I do see heavier (gen 3 style) single springs with adapters for gen 4, but if they have heavier dual spring systems I’m not seeing those.

Thank you, that’s good info!  

My 5.8” KKM is supposed to finally arrive tomorrow.  Sadly my impatient self is still waiting on the slide though.  When I get it all together I’ll just run the stock gen 4 RSA then.  I’ll plan on swapping it out every 2k just to be conservative.