"Like the current National Firearms Act (NFA), the 1934 Act required NFA firearms to be registered and taxed. The $200 tax was quite prohibitive at the time (equivalent to $3,581 in 2016). With a few exceptions, the tax amount is unchanged"
https://en.m.wikipedia.org/wiki/National_Firearms_Act
https://en.m.wikipedia.org/wiki/National_Firearms_Act