And machine guns aren't illegal in the US, as long as you have a Class III Licence. I know plenty of people who own .30 calibar machine guns (Browning M1919s) that they use for both reenacting as well as just target shooting.
EDIT: Most people use the term machine gun very broadly. It's usually defined as a squad type defense weapon, such as the M1919, M-60 or a SAW. M-16s are classified as assault rifles or automatic weapons.