Go to GlockTalk and ask
BUT
Get the Wolff steel guide rod and a 19 or 20 pound recoil spring if this gun if for CCW. Ask the Niner's group at GT which exact weight.
If you reload, its great to have a couple of springs to tune your loads to your needs from heavy hot loads with heavy springs to light springs for target rounds.
With a fixed or captured rod system, you're stuck.
Go with an uncaptured setup like Wolff's.
If memory serves me, the factory spring is 17 #.
With some hot Corbons or Powermax in there, the extra power recoil springs will suck up me of the recoil and allow for added accuracy while increasing lockup time just a tad.
And wolff springs are carried by Midway, Brownells, and other online dealers.
and Wolff has made his name in the spring business by making reduced power and extra power recoil springs, steel rods, magazine springs, revolver springs, etc.
ISMI, Glockmeister, Aerotek, Glockworks, Sprinco and the like just aren't invested in time, effort, material, tooling, and R&D like Wolff.
All Wolff does is springs. they are specialists.
If you shoot your Glock enough or go to a GSSF match or work in a gun shop long enough, you will see those Glock plastic rods breaking and grown men crying.
What would happen if you're in a defensive situation and your first shot misses and the rod breaks? You're toast.
Glock used to use steel but found out they could save money on plastic. And that's the only reason why platics ones are in there. They are acceptable but with a risk. And when it comes to coming home, I'm going to use the best defensive weapon I shoot well with the best parts, and the most potent and accurate ammo I can to go home. Ask any cop.
And stay away from that stainless steel and titanium crap. you don't need it. Just gimmicks and titanium is a joke. It may be a light and bendable as alumnium. No thanks, but they use titanium sheets to make airplane skins. What does that tell you? Not sturdy enough for me. I want good hard steel. No doubt.
Wolff now matte blacks his rods to match Glocks appearance.
Have them on every one of my CCW and comp guns.
Wolff - no doubt!