Why six 18-inch guns are a poor Iowa-class trade

What would an Iowa class armed with six 18-inch/47 guns be like?

Powerful per shell but poorly balanced; the navy would likely seek eight or nine 18-inch guns, while nine 16-inch/50s remain the better practical fit.

Six guns in three twin turrets repeat the awkward fire-distribution weakness associated with Renown and Repulse. If the United States truly wanted 18-inch weapons, it would probably stretch the hull for eight or seek nine guns rather than accept only six. The historical nine 16-inch/50 fit is judged adequate against expected opponents and better matched to Iowa's fast-battleship role than a slower Montana-style solution.