Pigpen - Here's a thought on this. If you could bear with me while I journey into the land of the hypothetical *grin*. The "equal and opposite" is happening on the slide, then after the slide reacts, through friction, on the frame. Only after that does the reaction move to your hand. If a gun could be made that had a frictionless slide and that slide could travel as far as needed to spend that reaction force, then I don't think your hand would feel any recoil at all. Ok, now that I'm done with hypothetical nonexistant guns lets move on to a more practical world. IF the way your hand feels recoil is by the slide acting on the frame then anything that absorbs the force of the slide prior to it's interaction with the frame (when it slams to the rear) should reduce the amount of recoil felt by the shooter. Right? So it would seem to me that a higher tension spring would make the slide spend more of its force to compress it, which would in turn cause the slide to slam into the frame with less force, which would then in turn cause the force of the recoil to be lessened. I don't know that a few ounds of difference in the spring tension is enough to actually do anything or if this is just a mind exercise that doesn't have much practical use, but it is my thoughts on the subject.