The 16"/50 caliber Mark 7 – United States Naval Gun is the main armament of the Iowa-class battleships and was the planned main armament of the canceled Montana-class battleship.
The Iowa-class battleship USS Iowa fires a full broadside of her 16"/50 (406 mm) Mark 7 guns. The roiling water caused by the stupendous muzzle blast creates an illusion of the ship moving sideways from the guns' recoil.
Yard workers hoist one of nine 16"/50 Mark VII gun barrels aboard the USS Iowa during her construction in 1942.
The 16-inch/50 caliber Mark 7 guns of the forward turret of the battleship USS Wisconsin (BB-64) fire at enemy targets ashore on the Korean Peninsula on 30 January 1952 during the Korean War.
Employees working with the automatic 16-inch powder stacking machine at Naval Ammunition Depot Hingham, Mass. during World War II.
The 16"/45-caliber Mark 6 gun is a naval gun designed in 1936 by the United States Navy for their Treaty battleships. It was introduced in 1941 aboard their North Carolina-class battleships, replacing
16-inch/50-caliber Mark 7 gun
…use against unarmored targets and shore bombardment. The North Carolina and South Dakota classes could also fire the 2,700-pound Mark 8 shell with the 16"/45 caliber Mark 6 gun, although with a shorter range. The Mark 6 gun was not as heavy as the Mark 7, which helped both battleship classes to conform to the limits of the…
Battleship armament: 16"/45-caliber guns aboard the battleship USS South Dakota (BB-57).
A cut-away diagram of the 16-inch turrets on board the North Carolina class