[expat2]

There is no need to print a barrel — that can be bought without legal constraints. The only part of the multi-part gun system which is “the firearm” is the lower receiver. That is not exposed to the strong explosive forces that the chamber or barrel see. In fact, AK-47 lowers are often made by bending light-gage sheet steel.

[GonzoGOP]

There is no need to print a barrel — that can be bought without legal constraints. The only part of the multi-part gun system which is “the firearm” is the lower receiver. That is not exposed to the strong explosive forces that the chamber or barrel see.

And this is the kicker. It will not be making guns from scratch, but making parts to convert one type of gun into another. With the printers you can turn an AR-15 into an M-16. You can convert your AK-47 to full auto. Government won't sell you high capacity magazines, a bit of spring steal and a 3D printer and their ban becomes unenforceable.

Back in World War One the US Army came up with the Pedersen Device, which could convert a bolt action rifle into a sub machine gun. It wouldn't be impossible to make something similar using a 3D printer.