^^As far as our friends at the ATF are concerned, yup, they're paperweights.
Because of it's modular design, the lower receiver is the only part of the AR platform that's considered to be a "gun", in that you need to purchase it through an FFL and pass a background check.
For the lower receiver to be considered a "gun" and be subject to regulation as such it has to be functional. Note that the pieces above are missing the milled pocket where the fire control group goes as well as the pin holes for mounting the same. Even though all the other machining steps are completed, you can't mount this to a rifle and fire it, therefore it's not a gun and not subject to any regulation whatsoever.
Now here's the kicker. As an American citizen in good standing with the law, I am legally allowed to build my own firearms for my own personal use as long as I do not sell, give away, or otherwise transfer the manufactured firearm.
http://www.atf.gov/firearms/faq/firearm ... s-assemblySo, we set up the CNC mill, take turns loading our paperweights into the machine and pressing the "start" button (thereby becoming the manufacturer of the firearm) and we all end up with functional lower receivers.
Hit the gun show, pay cash for a few over the counter components, and I have myself a shiny new non-serialized, untraceable, but still 100% legally obtained AR-15.
Yea, I could just go to an FFL, buy one and pass the 20 minute background check......but it's the principal of the thing.
