My memory is a bit fuzzy, but I seem to remember that prior to the amendment to the Gun Owner's Protection Act banning new manufacture of machineguns for civilians, there were around 128-134,000 machineguns registered. From the time the bill was introduced, until the May 16th, 1986 effective date, there were an ADDITIONAL similar number added. It took 52 years (1934-1986) to reach the first number, then a matter of weeks to reach the second. End result, in that few weeks, the number of transferable machineguns effectively doubled.
Unintended consequences of Charlie Rangles "Voice Vote" of the Amendment.