I'm interested in what it takes to convert a normal industrialised economy into a wartime economy, both present and in the past.
My knowledge of production techniques made it quite clear that it takes little more than a CAD (computer added design) file and some paperwork to turn a normal metal works company into an arms or ammunition manufacturer. The one process which looked to be rather uncommon for civilian purposes, yet vital to arms production was as far as I can tell the production of barrels.
One of the appropriate production processes for this is gun drilling, and it doesn't seem to be so very much uncommon in civilian production as I believed until recently.
The interesting thing about it is that while gun drilling requires a specialised machine, all other works needed to produce an all-metal firearm can be done on a single multipurpose, multi-tool machine (CNC machining centre). The CAD file, a gun drilling machine, a multi-purpose metal works machine, power supply and a roof are probably all that it takes to start a rifle factory nowadays. It's no wonder that so many companies have begun producing AR-15 rifles during the last years of irrational demand. It doesn't take much to set up such a company with its own production capacity and the profit margins were ridiculous.
It makes sense to outsource the stamping jobs (stamping is superior to milling for many parts) and the plastic parts production to other companies, of course. The bad thing about the plastics and stamped parts is that the tool (negative shape) is relatively expensive and more difficult to produce than the part itself.
I've found some nice info about the gun drilling technology, maybe someone else is interested, too:
A funnier, older video: