16"-50 caliber MK 7 naval gun

Developed by the U.S. Navy as the primary weapon for battleships of the Iowa-class, the 16"-50 caliber MK 7 naval gun represents a thoughtful set of design tradeoffs among gun weight, projectile penetrating power, range, and rate of fire. While the Iowas never engaged in combat with other battleships, but used these cannon for shore bombardment, many gunnery specialists consider it the best battleship main gun ever developed.

A common "what-if" is to consider an engagement between the Iowas and the contemporary Yamato-class battleships of the Imperial Japanese Navy. While such consideration cannot be based on the guns alone -- the Iowas were faster and had much superior fire control -- it is generally accepted that the seemingly weaker Iowas would have defeated the 18.1" gun-armed Yamatos. Their larger shells did not have as much penetrating power as those of the Iowas.

The U.S. had considered, while designing the Iowas, using an 18" gun, and also using the earlier MK 1 16"-45 caliber guns.