Fun historical fact, at the height of WW1, Germany was producing 12 million shells a month. Just in the preliminary bombardment at the Battle of the Somme the British fired 1.5 million shells. And now we're scrambling just to achieve one percent of the production we had a century ago.
All that industrial base is long gone, of course. Contrary to complaints about war profiteering, artillery shell production is not a terribly attractive business. The equipment can't easily be repurposed, it's not terribly sophisticated so the technological barriers to entry are low, you have one single customer, and the faster and better you provide your product the quicker the war ends and you go out of business. It's like combining the low margins and drudgery of running a factory that stamps out spoons, but with the added risk the spoons might obliterate the plant if a single worker makes a mistake.
All that industrial base is long gone, of course. Contrary to complaints about war profiteering, artillery shell production is not a terribly attractive business. The equipment can't easily be repurposed, it's not terribly sophisticated so the technological barriers to entry are low, you have one single customer, and the faster and better you provide your product the quicker the war ends and you go out of business. It's like combining the low margins and drudgery of running a factory that stamps out spoons, but with the added risk the spoons might obliterate the plant if a single worker makes a mistake.