[phobosanomaly]

I think you raise a really interesting point with this, and I want to offer a counterexample that I managed to come up with.

So, yes you can make an FGC-9 in your garage. Fair enough.

But are the barriers to manufacturing one in the garage sufficient to significantly reduce proliferation?

So, my example is the widespread absence of fully-automatic weapons in U.S. crime. Any schmuck with a lathe and a milling machine in the garage can crank out fully-automatic sub guns like it's Christmas in Sarajevo in 1993. But nobody does. You only very rarely hear about full-auto being used in the commission of crimes. Why? Perhaps the illegality, expense, and manufacturing hurdles (however small they might be) are just good enough to prevent meaningful proliferation in the way we see with semi-autos today.

The ammo thing is an interesting point too. I would think one of the biggest hurdles would be to homebrew ammo that was clean-burning enough not to immediately jam something like an FGC-9 in small calibers. I looked into cartridge case manufacturing and I guess there's a brass drawing process or something. I wonder how difficult it would be to base a design around CNC machined cartridge cases instead?