All of these manufacturing equipment and processes existed more than a century ago.
If you have a capable VMC, you can make the die and other equipment necessary to stamp shell casings from commonly-available parts and machinery.
From there, with a modern Dillon or Hornady reloading press, you can crank out thousands of rounds per day without issue.
Primers are a legitimately difficult thing to manufacture, but (good-enough) bullets, casings, etc. are completely doable.
I have no ability to make primers specifically, and wouldn’t even know where to start.
Imagine a flintlock 3d printed gun with hand cast lead balls: watch out redcoats!
[Primers are a legitimately difficult thing to manufacture]
thats a problem that may not endure. if a firearm is reengineered to use an electrode to detonate charge rather than a chemical primer, there is no need for murcury fulminate, just a piezo electric spark generator, and a few square cm of cerebral cortex.