L20 gun calibre depends on why Bayern stopped at 14 inches

If Bayern used 350 mm guns instead of 380 mm guns, what calibre would L20 receive?

Probably 15 inches, but only if the reason for Bayern's smaller guns did not also constrain the later design.

If the Bayern class carried 350 mm guns, the L20 might plausibly receive 15-inch weapons. That is not an automatic next step because the cause of Bayern's smaller gun matters. An industrial ceiling produces a different future from a German response to British 14-inch or 16-inch choices. Any projected design sequence must begin by identifying which constraint changed.