If your Gen 3 G20 is like my Gen 3 G20, you will likely find that your gun runs best with the stock RSA. I have fiddled with aftermarket parts, and they did not function 100% like the stock RSA. Increasing spring weight makes more abrupt felt recoil, and a snappier forward slide return. This can cause failures to feed like it did in my gun.
My gun runs full-powered everything with the stock barrel and RSA. 180 grain bullets from 850 fps to 1335 fps, and all speeds between. The G20 is pretty nicely dialed right out of the box.
What I would suggest is to run your gun with the stock setup and see if you have a problem that requires a "fix" with an aftermarket RSA. I bet you won't.
By the way, I buy replacement OEM RSAs from Lone Wolf Dist and swap them every 3000 rounds. They are inexpensive enough that it makes sense to have one or two spares.
Last edited by Taterhead; 06-16-2013 at 22:56..