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.
Hehe, I just grabbed the number off wolfram alpha's size comparison. Wouldn't surprise me if they are wrong, not sure where they scrape the data from. Anyway, my point stands, six microns is still stupidly small. Some dust or hair on the cutting edge and your precision is now out the window.