Has anyone here tried using CNC machines for gunsmithing as a hobbyist? Is that even feasible? What about 3-D printing metals instead of plastic? To be clear, I know little about either firearms or metal working, but it seems like it would be an interesting engineering challenge for a hobbyist.
Current hobby 3d printing of metals usually requires a clay-metal type of filament and sintering, usually by heat or laser to harden the metal, and often needing compensation for shrinking and a lot of other inconveniences.
The resultant pieces are "metal" but not strong enough for most internal firearms parts that need to be metal but not necessarily pressure-bearing like a barrel: most notably bolts and carrier groups, fire control group parts like triggers, hammers, sears, disconnectors.
You can't easily make a high-quality firearm a hobby mill, chiefly because the barrel needs to be made out of good steel and needs to be rifled. But the quirk in the US is that federally, only the receiver is the regulated part, and many types of receivers can be made out of plastic or aluminum. You can certainly use cheap three-axis CNC with some fixturing to make AR-15 receivers, for example, and many people did. Cody Wilson / Defense Distributed had this whole thing where they were selling CNC mills for cranking out guns.
You can also definitely make junk single-use guns using either technology, just like the 3D-printable "Liberator".
Routers don't have enough rigidity (this is why you don't see gantry mills except in huge sizes) for the kind of work you'll want to do. So much of your stuff will be one off that you're not going to have any speed advantage over a guy with a Bridgeport.
