On June 26, 1934 the United States Congress enacted the National Firearms Act The original purpose of the law was to ban or limit access to fully automatic weapons and handguns by using an extremely expensive tax instead of a complete ban; which was unconstitutional. Short barreled weapons were also added to the regulation so people wouldn’t try to get around the handgun regulations by just cutting down a rifle or shotgun. Before the passage of the bill, suppressors were added to the list and handguns were removed.Essentially the NFA tax, was an undue tax to suppress the common people’s right to posses suppressors.
A tax to limit the possession of an item that is legal to own and unconstitutional to ban should likewise be an unconstitutional tax. It is therefore a "burden Tax"