Folks shoot them at the gun range all the time. The machine gun needs to be classified as a C&R. Same applies to SBS (shorty shotguns).
Here is a link:
(3) persons possessing machine guns or short-barreled shotguns which, although designed as weapons, have been determined by the superintendent of the Bureau of Criminal Apprehension or the superintendent's delegate by reason of the date of manufacture, value, design or other characteristics to be primarily collector's items, relics, museum pieces or objects of curiosity, ornaments or keepsakes, and are not likely to be used as weapons;