Paint marine the only thing I can think of that might be causing your hopper to be up above your head when the tank is pushed into the front of your shoulder is if you are using a drop forward on the gun. If you are using one get rid of it and buy a pro rail which is made by custom products or any other similar no-drop. This will lower the hight of your hopper, help you keep a tighter profile when snap shooting and is a more stable platform when running and shooting.
hope this helps.
Andy.
hope this helps.
Andy.