I may well start working on it, starting with a version of avengers qvm.
As far as i know, FF is just points. If the xgun does 10 damage with every shot hit, if you shoot someone 30 times, you get however much of the ff setting set, if it were 1, you would get 30 damage too. It doesnt matter if they had full armor, it is still the bullets. I also dont believe that it works on buildables.