Less than 10k will get you a cnc milling machine. $5,000 you can build a wood CNC that can be converted to either 3D printer or cnc. Plans exist to build your own if money is really tight.
Where there is a will, there is a way. Governments may be able to push firearms manufacturing under ground, but it will not be able to stop gun manufacturing
Anybody with a Bridgeport and a lathe can make a barrel cam broach.
Ironically some of the world's very best metalworking cutting tools and technologies are now made by the Israelis.