16-inch /45-caliber gun

16-inch /45-caliber gun was a large-caliber naval artillery weapon designed for the United States Navy in the early 20th century. It armed the Colorado-class battleships and was intended to provide superior firepower against contemporary foreign capital ships. The gun saw extensive service during World War II, primarily in shore bombardment roles across the Pacific War.

Design and development

The development of the 16-inch/45 caliber gun was initiated by the United States Navy Bureau of Ordnance in response to the increasing size of battleships globally, particularly those of the Imperial Japanese Navy and the Royal Navy. Designed beginning in 1916, it was part of the armament for the new Colorado-class battleship, which followed the earlier Tennessee-class battleship. The weapon was engineered to fire a heavier shell (projectile) than the preceding 14-inch/50-caliber gun used on the New Mexico-class battleship. Key design features included a sophisticated Welin breech block mechanism and a thick, wire-wound construction for the barrel to withstand the immense pressures of firing. Initial production and testing were conducted at the Washington Navy Yard and by contractors like Bethlehem Steel.

Specifications

The gun had a bore diameter of 16 inches (406 mm) and a barrel length of 45 calibers, equating to 60 feet (18.3 meters). The complete gun and breech assembly weighed approximately 118 tons. It fired separate-loading ammunition, consisting of a bagged propellant charge and one of several shell types, including the 2,100-pound (950 kg) armor-piercing (AP) shell. Muzzle velocity for the standard AP shell was 2,525 feet per second (770 m/s). When fired at a 30-degree elevation, the maximum range was about 36,900 yards (33,700 meters); a high-angle 45-degree elevation, used for extreme range bombardment, could achieve approximately 44,800 yards (41,000 meters). Fire control was managed by advanced systems like the Mark 38 gun fire control system and associated Ford Rangekeeper.

Service history

The guns entered service aboard the USS *Colorado*, USS *Maryland*, and USS *West Virginia* in the early 1920s. During the attack on Pearl Harbor, the *Maryland* and *West Virginia* were damaged, with the latter sunk but later refloated and modernized. Throughout World War II, these battleships, and their main batteries, were extensively deployed in the Pacific Theater of Operations. They provided critical naval gunfire support during numerous amphibious assaults, including the Battle of Tarawa, the Battle of Peleliu, the Battle of Leyte Gulf, the Battle of Iwo Jima, and the Battle of Okinawa. Their primary role shifted from theoretical fleet engagements against ships like the *Yamato* to the systematic destruction of Japanese coastal fortifications.

Variants

The primary production variants were the **Mark 1**, the original model, and the improved **Mark 5**, which featured a slightly modified construction and was used on the modernized *West Virginia*. The **Mark 8** was a distinct variant, a lighter, higher-velocity gun developed later and used on the *South Dakota*-class and Iowa-class battleships; it is not to be confused with the earlier 45-caliber design. Additionally, the Army deployed a limited number of similar guns as coastal artillery, designated **16-inch Gun M1919**, at locations like the Fort Story military base.

Surviving examples

Several guns and their mountings are preserved as museum exhibits. A complete triple gun turret and guns from the USS *Massachusetts* are on display, though it is important to note that ship carried the different 16-inch/45 **Mark 6** gun. More directly related to the 45-caliber weapon, guns from the *Colorado*-class are mounted at the United States Naval Academy in Annapolis and at the Washington Navy Yard. Other examples can be found at the National Museum of the United States Navy and various veterans memorial parks, such as Mare Island.

Category:Naval guns of the United States Category:World War II naval weapons Category:406 mm artillery