This is also true that shells can be made on CNC lathe. At 26.8" each (68.1cm) you get 5 out of a 12' bar. Russia is shooting about 20,000 per day and on heavy day 60,000, Ukraine shoots considerably less. So to make one days worth of shells would take 4000 12' bars of material. What would be the machine time to make a shell?
Say it was 1 hr each for simple math so each machine could make 24 per day, so to make 20.000 shells in one day would need 833 machines. (or 1 machine could do it in 833 days- aprox 2 years and 4 months )
Check my math on these estimates
I would be surprised if there was enough material on hand to do 1/2 of that and how about the 800+ machines needed to keep up with usage? Granted we can probably cut this number in half while the current forges are also making some shells. I see this as a good discussion that has shown that this a non starter. In a real wartime economy all those machines would be making more important parts while the forges keep churning out the arty shells.