I understand the intent, but feel that there are so many other loopholes that put much worse weapons on the street than a printer. Besides, my prints can barely sustain normal use, much less a bullet being fired from them. I would think that this is more of a risk to the person holding the gun than who it's pointing at.
The reprap movement was exactly that. A self replicating rapid prototyper. While it never reached true replication, it got close enough to cause an explosive growth of the community. That, in turn led to the huge number of low cost suppliers and designs we have now.