If you look at this picture of a P-47 Thunderbolt’s wing, it’s obvious that the four M2 Brownings it holds are staggered. In other words, each one protrudes slightly further from the wing than the previous one. I assume this placement is deliberate, but don’t understand why it’s preferred. Does it have something to do with the gases emitted from one barrel interfering with the ballistics of bullets fired from an adjacent one?
I’d say it has to do with the way the three gun mechanisms are staggered inside the wing. IOW, if the muzzles protruded an equal amount, they would have to be further apart.
Xema got it in one. Think about it for a minute. Each gun has to have an ammo storage area. Each gun is the same overall length so to have room to store the ammo, you either need to stager the guns or space them further apart. According to this page browning ammo varies between 99 and 138mm long. so if you set each gun back about 6" from the one next to it, you can set the guns closer.
