The National Firearms Act, or NFA, governs the purchase, transfer, and creation of certain types of weapons. These weapons are interchangeably referred to as Class 3, Title II, and NFA firearms. "Class 3" refers to the Special Occupational Tax (SOT) stamp that is required for weapons dealers to sell such items. "Title II" is another term used to refer to the NFA itself; the Gun Control Act is "Title 1" of Federal firearms laws, and the NFA is "Title II".
Items regulated by the act broadly fall into the following categories:
While the NFA imposes a tax on certain types of weapons, its purpose was not to create a source of revenue. Instead, it was created to discourage the creation and transfer of NFA weapons due to their prevalent use in gangland crimes. To achieve this, the act required for the registration of all NFA weapons, as well as instantiated a $200 tax on the creation or transfer of NFA weapons. This tax was prohibitively expensive at the time of the act's creation.
Enacted in 1934, the NFA obligated all transferrers, creators, and owners of NFA firearms to register their weapons with the Secretary of Treasury. Due to this requirement, it was necessary for a holder of an unregistered NFA weapon to register it, thereby alerting state authorities to its existence. If the registered weapon violated state laws, the owner could be prosecuted for possessing the weapon.
This was found to be unlawful by the 1968 court case Haynes v. United States. The fifth amendment protects individuals from self incrimination, and the NFA of 1934 violated that protection. This lead to a revision (known as Title II of the Gun Control Act) of the NFA in 1968, which no longer required individuals to register their unregistered NFA firearms. It also prohibited the use of information gained from such a registration in a criminal proceeding. Additionally, the revision expanded the definition of machine guns, and added definitions for destructive devices.
In 1986, the Firearm Owner's Protection Act expanded the NFA's definition of "silencer" by making it include any components that could be used, and are intended to be used, as a silencer. It also prohibited the transfer or possession of machine guns, with exceptions for government agencies or firearms lawfully owned before May 19, 1986.