From my personal testing, I've been able to pop CCI primers with a 10lb mainspring and the factory weight FP spring BUT if you happen to not seat the primer fully, you will get light primer strikes. I've intentionally not seated primers fully and tested this with my pistol. Going with a reduced power FP spring and close to 1K rnds later, 10lb mainspring has been 100% ignition.
One issue I experienced just once recently, I found that the FP channel in my S2 was a little rough with the milling marks. With a reduce power FP spring, it was possible to dry fire the gun and depending on the orientation of the FP and FP spring, get it stuck in the forward position and the tiny FP stop fell out the next time I racked the slide. Fortunately I was in an indoor range and I managed to find my parts. Had it been in an outdoor range, I'd probably be shooting my Glock at today's BB course while waiting for parts to come in. I've since polished my FP channel and FP and tested pushing the FP in repeatedly with a punch seeing if I could get it stuck. About 700rnds later, still holding up.
A 13lb mainspring should not require a reduced power FP spring else your FP will just get jammed into the front of the channel and get stuck there. I would recommend the reduced power FP spring if you go with a 12lb or lighter spring.
As for recoil springs. If you're shooting factory loads and they're on the hotter side, I would probably suggest a 13lb spring. If you reload your own ammo and it is around the 128-130PF, a 11lb spring works nicely without beating up your pistol. I'm told that you can even go down to an 8lb spring if you're shooting mild 147gr reloads which I might try eventually.
I've been seeing TiteGroup at my usual retailers.
