The stackable bonus needs to be removed.
When the Golden Gun was created, it wasn't intended to be as common as it has become. There's around 50 running around on W12, and I don't even want to know the numbers for Arizona.
Let the +15 damage bonus go in to effect for the sector, but only from one Golden Gun. Precise Winchesters hit up to 327, Golden Guns hit up to 353. If that golden gun dies, then the next golden gun in the sector has his +15 take effect. Same goes for the sector bonus of +3 attack and +3 defense.
With this the golden gun would help and is still desirable, but would not entirely throw a world off balance. No need for a boycott.