I think i have a feeling of what you want. I might look into it for my next game but right now i grew tired of my old codebase. There would be so many things to fix that right now are only loosely hanging together.
The two gun modes were supposed to have different purposes. I did never explain it in the tutorial though. The one where the sets of barrels are linked have higher muzzle velocity and accuracy. The other one does high rate of fire and inflicts more damage but spreads a lot more.
As it is right now, it is a question of range, but what I actually wanted to have is a simulation of armor. Only when coupling the guns, you would be able to penetrate armored objects. In the next game maybe.