Just a Technicality, The Sten Sputter Gun.
In 1982 a man named William M. York had a brilliant idea. He created his own fully automatic weapon that he claimed defied federal law and were legal to own. Under the name “York Arms Co.” he took semi-automatic Sten submachine guns and modified them to full auto. Federal law at the time defined a machine gun as firing multiple rounds with a single pull of the trigger. York thought he saw a loophole, his guns didn’t need a trigger!
Instead his Sputter Gun operated by releasing the bolt mechanism. Once the bolt was released the gun would fire continuously (and uncontrollably) until the 32 round magazine was depleted. He also added a forward grip and cuff shaped butt plate to better “control” the device. York advertised the gun as a weapon for those “who want the fun and excitement of owning and firing a fully automatic weapon without the government tax and red tape.”
In 1985 the ATF caught on to York’s creations and ordered him to cease and desist. He was also ordered to recall his Sputter Guns and issue a full refund to all his customers. This proved unnecessary since no one actually purchased any of his firearms.