How much of a difference will this make? Surely if they are still raking it in, (even if they switch off to the EU occasionally), and they are selling to countries outside of Europe, they can afford to build more low grade weapons for a long time.
Economics is weird to me.
Manufacturing involves, what? Buying raw materials. Buying fuel to move the materials around by the truckload and trainload. Buying energy and water for the manufacturing process. Paying workers in - ultimately - food and shelter to carry out the process.
I think we can safely say Russia has adequate sources of energy, water, and fuel internally, and doesn't need to pay for them. The state can seize what it needs directly. Or pay for them in rubles, or whatever internal, within-their-own-borders economic bookkeeping they end up doing.
Same with their workforce.
Where are the raw materials coming from, though?
If the whole economic envelope is inside their borders, they wouldn't need to sell anything to anyone else to keep manufacturing. Pay their own people rubles for the raw materials. Pay their own gas and electric and water companies in rubles for their services. Put their own fuel into their own trains and trucks. Etc.
I guess there must be some sort of leveraging involved. Russian factories are agreeing to do the work based not on an influx of ready cash, but on the basis of their customer's good credit, underwritten by phat deposits in international bank accounts, from buyers of Russian oil.
Maybe future war crimes tribunals will be less concerned with bringing individual conspirators to justice, and more concerned with ensuring punitive sanctions persist after the war is over, until the credit of the enabler is ruined and their speculative business collapses.