Title 18, Section 922(o)
Without looking it up, I will presume this is the change to the
US Code brought about by the Hughes Amendment.
Between 1934 and 1986, about 128,000 machineguns were
registered under the National Firearms Act registry, with little
or no crime use of NFA registered guns--only one murder (by
a police officer who obviously had access to other firearms).
Some people called the machinegun registry a successful
control law. So what did the antis do when they had the
opening? They tacked the Hughes Amendment onto the
Firearms Owners Protection Act as a "poison pill"--banned
future NFA MG registrations 19 May 1986.
Title 18, Section 922(o) is a monument to the fact that
antis do not want "control"--they want bans. To the
prohibitionist mentality reasonable legislation is prohibition.
The most restrictive registration program was not enough--
the Hughes Amendment turned it into a defacto ban.