12"/45 caliber Mark 5 gun

The 12"/45 caliber Mark 5 gun was a US naval gun that first entered service in 1906. Initially designed for use with the Connecticut-class of pre-dreadnought battleships, the Mark 5 continued in service aboard the first generation of American dreadnoughts.

Country Name Origin Year
United States of America 1906
Country Name Operational Year Retirement Year
United States of America 1906 1930 View

The 12"/45 caliber Mark 5 naval gun was designed as an incremental improvement upon the preceding American naval gun, the 12"/40 caliber Mark 4. As such, it was a very similar weapon, having been lengthened by 5 calibers to allow for improved muzzle velocity, range, and penetrating power. Designed to the specifications of the Bureau of Ordnance, the Mark 5 was constructed at the U.S. Naval Gun Factory in Washington, D.C.

The Mark 5 entered service in 1906 and remained the primary battleship gun for all American battleships commissioned before 1912, at which point it was replaced by the 12"/50 caliber Mark 7. All told, the Mark 5 would arm 14 battleships of five different classes, making it the most-utilized main gun in American battleship history. Despite this distinction, the only Mark 5 guns ever to be fired in anger were actually in Greek, and not American, service. The ex-Mississippi class battleships Kilkis and Lemnos, sold to the Royal Hellenic Navy in 1914, fought in both the Allied Intervention in the Russian Civil War, and the Greco-Turkish War. Though during World War I the Mark 5 would cross the Atlantic for duty aboard two of the American battleships serving in the 6th Battle Squadron of the Grand Fleet, it was never fired in any engagement, as no battles were fought with the German High Seas Fleet in 1918.

Type Naval gun
Place of origin  United States
Service history
In service 1906-1930
Used by  United States Navy
 Hellenic Navy
Wars World War I
Russian Civil War
Greco-Turkish War
World War II As coastal artillery
Production history
Designer Bureau of Ordnance
Designed 1903
Manufacturer U.S. Naval Gun Factory
Weight 53 tons
Barrel length 45-foot (13.716 m) bore (45calibers)
Shell 870 lb (394.6 kg)
Caliber 12-inch (304.8 mm)
Elevation -5° to +15° 
Rate of fire 2–3 rpm
Muzzle velocity 2,700 ft/s (820 m/s)
Effective firing range 20,000-yard (18,288 m) at 15° elevation
30,000-yard (27,432 m) at 47° elevation As coastal artillery

End notes