The good thing about changing springs is that they are easy to change back if they don't work. I've only had trouble with primer ignition with wolff mainsprings when firing rimfire rounds, and only DA, not SA. I do not ground down my mainspring screw.

However, any gun that I am planning on using defensively is always tested rigorously with my defensive carry ammo of choice before I finalized the spring weight. It should have a good number of trouble free rounds through it before it should be counted on. Most of my guns are not for defensive carry, but for range fun.

Now, rebound springs are a bit of another matter. To go lower than 16lbs, some parts have to be polished to get decent reset time. And you can't put back metal that you've polished off, so extreme care is the watchword.