I think the issue is that it is not a 3D printing problem. Plenty of hobbyist reload and self manufacture bullets it requires a simple reloading press. Most of the components can be self manufactured if one desires, as the other child poster has already said, smokeless powder is probably the hardest to manufacture but not impossible.

It’s not yet documented in the 3D printing community, but it’s not an unsolved problem. Both priming compound and black powder are fairly easy to make. Smokeless powder is a bit more difficult, but not much.