The National Firearms Act (NFA) covers firearms or certain attachments that can also be referred to as Class III items. These include short barrel rifles (SBR), short barrel shotguns (SBS), machine guns, destructive devices, silencers and a classification called any other weapon (AOW). NFA/Class III items are a federally regulated item and require the buyers fingerprints to be taken to submit for an FBI background check and either a $5 or $200 tax stamp, depending on classification, paid to the Bureau of Alcohol, Tobacco, Firearms and Explosives.