Actually....
The National Firearms Act was in 1934. Before that, anyone could walk into a store and buy a Thompson. (Well, anyone who could afford one!)
The NFA DID NOT ban fully automatic firearms, it simply required purchase of a Federal Tax Stamp in order to purchase a fully auto. Until 1986, pretty much any law abiding citizen could purchase a new M16, Glock 18, HK MP5 and other newly manufactured firearms. States had specific laws (some banning them) but in many you just needed the tax stamp and comply with state laws.
After 1986 and now, most people can purchase fully auto firearms manufactured prior to 1986. I know people that legally own HK MP5's, M16's, M16 full auto converters, 30 cal machine guns, and a guy that collects MP 40's. I have often considered purchasing a M16, last I looked they were about $20k.
There are tens of thousands of legal fully autos in civilian hands, and none of these legal arms have even been used in a crime. If they did, you would never hear the end of it.