Mini-gun is right! My next project is 2 Mini-Draco pistols mouted to the outside of the doors, with a 15 degree turning radius on the mount, and space to use the 75 round drum magazines. So you could basically reach your arm out and fire!
I live in Montana, so, Yes that is legal here to mount my gun outside. However, Drive-by shootings are illegal and highly discouraged. Don't try this at home!!