Wing guns necessarily are aimed above the wing's cord line. The guns start out several feet below the LOS through the gunsight, and convergence is usually set far enough away that the bullets are arcing back slightly down from above the LOS when they cross it. Thus, when you fire, the tracer trail will always be at a higher "angle of attack" than the wing, so that as the wing moves forward, it gets under the smoke. This is why the smoke appears to be above the wing. And even at high G, the guns are still at a "higher angle of attack" and the plane's turn radius isn't anywhere near tight enough to keep the wing from getting under the smoke.
