The main weak point of Hambone, level one end-boss, is his large Gattling gun. That's right, just keep shooting as fast as you can at his gun and you will waste his energy and keep him from shooting at you. During the brief moments when he is not shooting, fire at either his head or legs but be sure to keep shooting the gun. As the screen moves from the right side of the hallway to the left, grab the shotgun that appears! Marksman lose very little energy on Hambone.