On "The Crow's Nest", fly towards the highest point of the roof you can, aiming to hit the center. Keep holding the B and Y buttons until you hit it. If you aimed right, you should be teleported into a metal pipe structure. Get to the end of this metal pipe structure and you should be teleported back to the main area. The orange balls of ammunition that you can normally obtain should have turned blue, and will now never run out unless you get hit.