The discussion moves beyond the simple question of whether a large gun can be manufactured. Bigger cranes and deeper quenching wells are solvable industrial problems, not the main obstacle. A workable weapon needs a barrel that will not sag or fail under pressure, shells and guns that can be moved safely, and a turret system capable of handling the mass. Those linked constraints make twin 20-inch mounts progressively less attractive than triple 18-inch turrets and make a nine-gun 18-inch Incomparable more credible.
Notable Point · 19:34-22:52
The engineering problem behind 20-inch guns
A 20-inch naval gun is constrained less by a single crane or pit than by barrel metallurgy, weight, handling, and turret machinery.