14"/50 caliber gun

These guns were more powerful than the main gun mounted on the previous three classes of US battleships (the, and es), the 14"/45 caliber gun. A newer version known as Mark B was proposed but ultimately not used for the s.

• Name — 14"/50 caliber gun • Origin — United States • Type — Naval gun • Is Ranged — "yes" • Is Artillery — "yes" • Service — 1918–1956 • Used By — US Navy • Wars — World War II • Designer — Bureau of Ordnance • Design Date — * Mark 4: 1916 • Mark 7: 1930 • Mark 11: 1935 • Mark B: 1937 • Manufacturer — U.S. Naval Gun Factory • Number — * Mark 4 Mod 0: 39 (Nos. 82–120) • Mark 4 Mod 1: 80 (Nos. 121–200) • Variants — Marks 4, 6, 7, 11 and B • Weight — 179614 lb (with breech) • Length — 59.5 ft • Part Length — 700 in bore (50 calibers) • Cartridge — * Mark 8: 1402 lb Armor-piercing (AP) • AP Mark 16: 1500 lb AP • HC Mark 19: 1275 lb High explosive (HC) • Caliber — 14 in • Rate — * Marks 4, 6, 7, 11: 1.75 rounds per minute • Mark B: 2 rounds per minute • Velocity — * Mark 4 and 6: 2800 ft/s • Marks 7, 11, and B: 2700 ft/s AP • Marks 7, 11, and B: 2825 ft/s HC • Reduced charge: 1935 ft/s AP • Reduced charge: 2065 ft/s HC • Range — 25000 yd at 15° elevation HC • Max Range — 36800 yd at 30° elevation AP • Recoil — 48 in • Elevation — * New Mexico-class: -5° to +15° (later increased to 30°) • All other: -5° to +30° • Traverse — 306° max 297° min • Illustration — The 14"/50 caliber guns on Tennessee fire in support of the invasion of Okinawa

The 14-inch (356mm), 50 caliber gun was the weapon chosen as the main armament on the when they were originally designed, but it was later switched to the 16"/50 caliber Mark 2 gun in a 1917 redesign. The ships were eventually canceled in 1922 after the Washington Naval Treaty was signed. The 14"/50 caliber gun was designed in 1916 and entered service in 1918 on the s. The guns were capable of firing a 1402 lb armor-piercing (AP) projectile at an angle of 15 degrees, to a range of 24000 yd. Each gun weighed approximately 179614 lb, including the breech, and was 59.5 ft long. The propellant charge used for the ammunition weighed 470 lb and was contained in four bags. Each Mark 4 built-up gun consisted of a tube, liner, and a screw box liner with a separate screwed-on flange. Three hoops and two locking rings were also included. The Mark 6 was slightly different in that it contained a single step taper liner and uniform twist rifling. Downward-opening Welin breech blocks and Smith-Asbury mechanisms were used on both Mark 4 and Mark 6 types. The Navy encountered dispersion problems at extreme ranges with these guns in the 1920s. Several methods were used to correct these problems, including correction of range tables for errors, addition of delay coils, reduction of chamber volume, and improvement of shot seating. The Mark 7 was designed in the 1930s and entered service in 1935. This gun included a smaller chamber, a shell-centering cone, a single-slope band seat, uniform rifling, and a tube locking ring. The Mark 11 was introduced later, with chromium plating added to the bore. New Mexico- and Tennessee-class battleships were rearmed with 14"/50 Mark 11 guns, with the Tennessee receiving the upgrade in 1942. The dispersion problems that existed with Marks 4 and 6 were corrected with these guns.

A newer version of the 14"/50 caliber gun, Mark B, was designed in 1937. It was the original gun intended for use on the s, in three quadruple turrets. The Mark B was the most powerful 14 inch weapon ever designed by the United States, being simpler and lighter than the older versions. However, the prototype of this gun was not completed because the 14 inch treaty limit was rescinded in 1937 which allowed the new battleships, despite being already under construction, to be modified in order to carry 16 inch/45-caliber Mark 6 guns.

The 14"/50 caliber gun was installed on five battleships: New Mexico, Mississippi, Idaho, Tennessee, and California. Although both Tennessee and California were damaged during the attack on Pearl Harbor, both of these ships' guns, along with the other three, were used in the Second World War in shore bombardment duty. Mississippi, Tennessee, and California all participated in the last line battle to date: the Battle of Surigao Strait. As shore bombardment platforms, these five battleships participated in all phases of the war, such as the Aleutian Islands Campaign (Idaho, Tennessee), the Battle of Kwajalein (New Mexico, Mississippi, Idaho, Tennessee), and the Battle of Guam (New Mexico, Idaho, Tennessee, California).

• Ship — Gun Installed — Gun Mount • (1916 design) — Guns: 14"/50 caliber (never installed) — Turrets: * 2 × two-gun turrets (never installed) * 3 × three-gun turrets (never installed) • Guns: 14"/50 caliber — Turrets: 4 × three-gun turrets • Guns: 14"/50 caliber — Turrets: 4 × three-gun turrets • (1935 "B" proposed design) — Guns: 14"/50 caliber (never installed) — Turrets: 3 × four-gun turrets (never installed)

During World War I, five of the 14"/50 caliber guns served as railway guns on the Western Front in France. Gun No. 119L2, a Mark 2 gun on a Mark 1 Railway Mount No. 148, is located at the US Navy Museum, Washington Navy Yard, Washington, D.C. Gun No. 19, on an M1918 Railway Mount No. 9, built by the Marion Steam Shovel Company, is located at the US Army Ordnance School, Fort Gregg-Adams, Virginia.

• 14-inch gun M1910 US Army coast defense equivalent • BL 13.5-inch Mk V naval gun contemporary British equivalent to Marks 4, 6, 7, 11 • BL 14-inch Mk VII naval gun contemporary British equivalent to Mark B • Vickers 14 inch/45 naval gun contemporary Vickers-designed Japanese equivalent