What is a class three weapon?

Class three weapons include short-barreled rifles and shotguns, suppressors, destructive devices and machine guns according to Guns and Ammo. They require, by law, a NFA registry transfer of registration for legal possession.

As of 2014, there is a $200 tax to manufacture a class three weapon and another $200 tax to transfer the registration of a class three weapon. To manufacture one of these weapons, approval from the ATF is needed. To buy a class three firearm, one needs an ATF approval after transferring the weapon from one registered owner living in the same state as the new registered owner.