Here is another issue: some planes (Mossi, P39 for sure) have more lines of convergence than types of guns.
The Mossi has four 20mm and four .30 cal, but yet there are white, green and blue lines (). What gives?
The P39 has FOUR colors (white, green, blue, and yellow). There are four .30cal, two .50cal, and a 20mm (or 30mm?). Why not just three lines of convergence?
There are others too, I just cant remember them off the top of my head atm.