I like the idea of stray bullets when shooting into melee. If you miss because of the -20, then you randomly hit another target in melee. It works especially well for single shots. I don't like the alternate rule for FA and SA. Allocating each hit to another target seems too much. I like the idea of some/most of the bullets hitting the intended target, while a few strays might hit unintented targets.
Does anyone else use a rule for FA and SA in melee? If so, what is it?