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?
BTW, here’s a shot of the entire plane where it’s still easy to appreciate that the M2’s are staggered in the same way.