[Lee Stewart]

The USS Missouri - last of the Iowa Class Battleships. She has nine 16-inch/50-caliber Mark 7 Guns. OK - so what does that mean?

The nomenclature of the Mark 7 can be a little confusing, however, as it basically meant that the guns were 50 calibers long – or 50 times their 16-inch bore diameter, which made the barrels 66.7 feet (20.3 meters) long, from chamber to muzzle. Each gun weighed about 239,000 pounds (108,000 kg) without the breech – and 267,900 pounds (121,500 kg) with the breech. More importantly, the Mark 7 gun was able to fire projectiles weighing from 1,900 to 2,700 pounds (860 to 1,220 kg) at a maximum speed of 2,690 feet per second (820 m/s). The range was up to 24 miles (39 km) and at maximum range, the projectile could spend almost a minute and a half in flight. Another common misnomer about the Iowa-class is that it had triple gun turrets, but this is not technically correct. In fact, the turrets were actually “three-gun” and not “triple” as each barrel could be elevated and fired independently. Moreover, each gun could be elevated from -5 degrees to +45 degrees, moving at up to 12 degrees per second. The turrets could also rotate about 300 degrees at about 4 degrees per second.