Could Japan supply Germany with 41 cm guns?

How quickly could Japan deliver heavy battleship guns to Germany in the late 1930s?

Existing-pattern 41 cm guns might arrive around 1937, but a custom 42 cm weapon would take several years and disrupt Japan's own 46 cm development.

Production capacity matters more than diplomatic possibility alone. Japan's existing 41 cm manufacture and refit line could support an export order, perhaps using relined weapons. A custom 42 cm calibre would require calculations, tooling, and scarce research infrastructure. That work would compete directly with the Japanese 46 cm programme. Britain faced a comparable constraint after specialist ordnance facilities closed, narrowing the gun options available for the King George V class. Earlier budget decisions can therefore become hard design limits years later.