5-inch /51-caliber gun

5-inch /51-caliber gun was a medium-caliber naval artillery piece designed by the United States Navy's Bureau of Ordnance in the early 20th century. It served as a secondary and primary battery gun on numerous dreadnoughts, cruisers, and destroyers, and was widely adapted for coastal artillery use. Renowned for its high muzzle velocity and flat trajectory, it remained in service through both World War I and World War II.

Design and development

The gun was developed beginning in 1910 to fulfill a requirement for a powerful, rapid-firing secondary weapon for the new generation of American dreadnought battleships, such as the ''Florida''-class. The Bureau of Ordnance sought a weapon capable of defeating the thin armor of contemporary destroyers and torpedo boats at long range. The design emphasized a high muzzle velocity, achieved by its 51-caliber length, which provided a very flat trajectory for improved accuracy against fast-moving surface targets. Initial production contracts were awarded to major arms manufacturers like Bethlehem Steel and the Midvale Steel and Ordnance Company. The gun used a wire-wound construction method common for the era and featured a Smith-Asbury breech mechanism for reliable operation.

Service history

The gun entered fleet service aboard the USS ''Utah'' in 1911 and quickly became a standard secondary battery armament on American battleships, including the USS ''Texas'' and the ''Nevada''-class. During World War I, a number of these guns were supplied to the Royal Navy for arming merchant ships and Q-ships against German U-boats. In the interwar period, it was fitted on cruisers like the ''Omaha''-class and early destroyer leaders such as the ''Clemson''-class. In World War II, while obsolete for fleet actions, it saw extensive use as coastal defense artillery in places like Pearl Harbor, Dutch Harbor, and Newfoundland, and remained on many older vessels in secondary roles, including the USS ''Arkansas'' which provided fire support during the Normandy landings.

Variants

Several marks were produced, with differences in construction and mounting. The **Mark 7** was the early wire-wound model for battleship secondary batteries. The **Mark 8** was a later model with a slightly modified chamber. The **Mark 9** was designed as a lower-weight version for installation on destroyers. The **Mark 14** and **Mark 15** variants were purpose-built for submarine deck gun use on vessels like the USS ''Argonaut'' and the USS ''Narwhal''. Different pedestal, single, and twin mounts were developed, including the widely used **Single Pedestal Mount** and the **CP** (Central Pivot) mount for coastal defense.

Specifications

The gun had a caliber of 5 inches (127 mm) and a barrel length of 255 inches (51 calibers). It fired a separate-loading, bagged charge round; the standard armor-piercing projectile weighed approximately 50 pounds (23 kg). Muzzle velocity was 3,150 feet per second (960 m/s). Its maximum range with a 20-degree elevation was about 17,000 yards (16,000 m), though some coastal mounts achieved slightly greater range. The typical rate of fire was 8 to 9 rounds per minute. The complete gun and mount assembly weighed roughly 5 tons.

Surviving examples

Numerous guns survive as museum pieces and memorials across the United States and Commonwealth nations. Notable displays include guns at the Washington Navy Yard in Washington, D.C., the Battleship Cove museum in Fall River, Massachusetts (from the USS ''Massachusetts''), and the Royal Australian Navy Heritage Centre at Garden Island, Sydney. Several are also preserved as coastal defense guns at former U.S. Army Coast Artillery posts, such as Fort Miles in Delaware and Fort Story in Virginia.

Category:Naval guns of the United States Category:World War I naval weapons Category:World War II naval weapons Category:5-inch artillery