Talk:Battleship

Perhaps you can answer a question I have about guns on a battleship, an answer I have not been able to find on internet searches. The most common configuration on later battleships were 8 guns in 4 turrets or 9 guns in 3 such as the Iowa class. Why was a 12 in 4 not built? I thought it could be due to displacement but even the proposed German behemoth "H" battleships only had 9 (main) guns, if very big ones. Thanks.