The practical limits of a 12-inch 70-caliber gun

How effective would a 12-inch 70-caliber naval gun be with Second World War technology?

It might be made to work with a major development effort, but its roughly 70-foot barrel, propellant demands, and manufacturing complexity make a 12-inch 50-caliber weapon the more practical choice.

The answer focuses on the consequences hidden inside the caliber-length figure. A 70-caliber barrel is extraordinarily long, demands a large propellant charge, and intensifies the precision and strength requirements throughout the weapon. Wartime technology might solve those problems, but a shorter 50-caliber gun offers a more credible balance of performance and reliability.