A distinction between a self-defense firearm and a target gun must be drawn. A target gun is like a prima donna who wants to be fed a special ammunition diet. She may not or will not work with all types of ammo or under non-match conditions.
A self defense firearm must be reliable. Period. It must shoot first time, every time and lightening the spring could compromise ignition. Lightening the rebound slide spring could slow the rebound slide down; impeding its safety function. If you're 586 is a target/range gun which you won't use in self defense, no problem. Enjoy. If you want it to do double duty, ensure its reliability by testing it with the ammunition you plan to use for self defense. Have fun.