Gun Control & RKBA

90% of all firearms? The AR system isn't THAT popular yet. And if they mean pistols, like the Glock, well, they DO have frames that are serialized. The FAL system's upper receiver bears the serial #, per BATF. Selling a 100% stand alone frame without a serial # is illegal. An 80% frame is not exactly "quickly and easily" made. If you don't have it milled correctly, or holes drilled properly, the firing components won't work. Yes, you can make a gun for your own use, and not serial # it. Selling it is illegal. Using it for murder was illegal also, the last time I looked.