The discussion distinguishes problems that can be addressed with larger infrastructure from the deeper problem of producing a very long, heavy gun barrel that will not sag. Bigger cranes and deeper quenching facilities require investment, but the metallurgy and accumulated development behind a workable 20-inch gun could take decades. Money can enlarge plant quickly, but it cannot instantly replace the chain of research and production experience behind a reliable weapon. An 18-inch armed ship is presented as a more plausible contemporary outcome than a six-gun 20-inch design, with a warning that the Japanese design reference needs checking.
Chapter · 2:13:42-2:16:02
Why a 20-inch gun is more than a scaling problem
The discussion argues that early-20th-century cranes and facilities could be enlarged, but metallurgy and barrel stiffness make a 20-inch naval gun a far harder proposition.