Mark 7 16-inch/50-caliber Gun

A US Navy sailor stands beside one of the gargantuan 16-inch/50-caliber Mark 7 guns mounted in Turret No. 1 aboard the battleship USS New Jersey. These guns were absolute monsters. Each weapon weighed approximately 267,904 pounds and could fire a 2,700-pound armor-piercing shell at roughly 2,500 feet per second. At maximum elevation, the Mark 7 could strike targets more than 23 miles away. The nine Mark 7 guns formed the main armament of the Iowa-class battleships, arranged in three enormous triple-gun turrets. Although three guns were housed inside each turret, they could be loaded, elevated, aimed, and fired independently. This allowed the crew to engage targets with individual guns or unleash the entire battery in a devastating nine-gun broadside. The Iowa-class battleships and their guns saw combat across several generations. They were employed during World War II, the Korean War, the Vietnam War, the Lebanese Civil War, and the Gulf War. Decades after their construction, they remained capable of delivering an extraordinary volume of accurate naval gunfire against enemy positions far inland. Complementing the Mark 7 was the Ford Instrument Company Mark 8 Rangekeeper, an advanced analog fire-control computer. Working alongside radar, optical rangefinders, gyroscopes, and other fire-control equipment, it calculated a firing solution while accounting for the movement of the ship, the movement of the target, wind, range, shell flight time, and other constantly changing variables. This sophisticated fire-control system gave American battleships a major advantage, particularly during the war against Japan. The guns possessed tremendous power, but their effectiveness ultimately depended upon the ability of the crew and the fire-control system to place thousands of pounds of steel onto a distant, moving target. The Iowa class could fire a full armor-piercing broadside weighing 24,300 pounds. Among battleships, this was exceeded only by the Japanese Yamato class, whose nine 18.1-inch guns could throw an even heavier broadside. The Mark 7 was a built-up naval gun constructed from multiple reinforced components surrounding the barrel. This strength was essential, as each firing generated approximately 304 million foot-pounds of muzzle energy and placed enormous pressure upon the weapon. Typical of major American naval guns built during the 1940s, the bore was chromium-plated to reduce wear and extend barrel life. Even so, every shot subjected the gun to forces almost impossible to comprehend. More than eighty years after their introduction, the Mark 7 remains one of the most powerful and recognizable naval weapons ever placed aboard an American warship.