Well I might as well throw my 2 cents in this argument
I only have experience with my Glock 21 , nothing else .
That said ,
The Glock has a factory 17 lb recoil spring , works great .
I bought all the Glockmiester and ISMI springs I could get and tried them all .
All springs don't work with all loads .
On Glocks , if you have to light a recoil spring you must install a lighter firing pin spring !
Felt recoil is a subjective thing , some people don't mind the " crack " of a
9mm and dislike the " push " of a 45acp
With reloads I have made my 45 acp " crack " ( or snap if you like ) and
" push "
Most people who have shot my pistol prefer " push "
On my gun " push " = 230 grain and low to moderate velocity .
Back to the recoil springs .
in my gun , using the same loads if you install a heavier spring ( 19 lb ) you "feel" more recoil , using a lighter spring (15 lb ) you " feel " less recoil .
Using to light a spring will allow the slide to hammer back to fast and hard and will eventually cause damage .
Most manufactures will put a heavy enough spring in to work with all factory loads and not beat the gun to death .
If you load your own , you can tailor the spring to your load , the plus is when done right the gun will cycle quicker with less felt recoil .
The reason a lighter spring transmits less felt recoil is it takes less force to move the slide so less force is applied to the shooters hand .
With a heavier spring it takes more force to move the slide , this extra force is transmitted to the shooters hand .
Now feel free to shoot my experiences to pieces .
