https://en.wikipedia.org/wiki/Shell_Crisis_of_1915
https://en.wikipedia.org/wiki/Mark_14_torpedo#Supply_and_pro...
https://en.wikipedia.org/wiki/American_services_and_supply_i...
Etc. etc. etc...
I think that seeing the bottom of the barrel is euphemistic for "guys, we really have to settle this contract" -not "there are no more shells"
The WW3 factions are lining up, so it seems inevitable that the sides would start to arm themselves in preparation.