The Colt M-16 is not a machine gun.
The M-60 is a machine gun, belt fed.
The 20mm is a mounted machine gun. This is the one you need to bolt the mount to the floor of your pick-up. Or you will crash through the rear window and fly through the front window of your pick-up with the first shot. Those are the belt-driven ones. And those shells are BIG.
dont you consider full auto a machine gun?