Shoestring Machine Gun

In September 2004 the ATF decided that a 14 inch long shoestring was considered a machine gun:

Here is an official letter stating the facts:

In 2007 the ATF decided the shoestring alone was not a machine gun. It was only considered one when added to a semi automatic rifle in order to increase its rate of fire:

Thank god they reversed their 2004 ruling. It would have been pretty difficult to prosecute the entire shoe wearing population of the United States for constructive possession of a machine gun. :lol:

The first picture in this post is allegedly a “registered” shoe string, that the owner paid to be able to use legally. That metallic tag apparently has a serial # on it.

This raises a couple of questions in my mind…

Why is the ATF so specific of the type of string used? Why is the ATF so specific with the length of the shoestring?

I wonder what would happen if someone was caught using a 13 inch piece of fishing line? I suppose since it still would increase the rate of fire, it would be deemed a machine gun no matter what type of string or length.