Not sure if it's a bug or intended but when the gunner on a buff fires it appears as if ALL the guns are firing. So while yes it may appear that the nose guns might be shooting through the fuselage, trust me, they're not. Only the guns that can be brought to bear on you will be actually shooting bullets at you, the rest are just phantom tracers.
If you want to see this for yourself just have a gunner jump on board and watch him move the guns around and fire. You'll see them all move and fire at once.