8-inch/55-caliber gun


The 8"/55 caliber gun formed the main battery of United States Navy heavy cruisers and two early aircraft carriers. United States naval gun terminology indicates the gun barrel had an internal diameter of 8 inches, and the barrel was 55 calibers long.

Mark 9

These built-up guns weighed about 30 tons including a liner, tube, jacket, and five hoops. A down-swing Welin breech block was closed by compressed air from the gas ejector system. Loading with two silk bags each containing of smokeless powder gave a projectile a velocity of 2800 feet per second. Range was 18 miles at the maximum elevation of 41 degrees.

Mark 12

These simplified built-up guns eliminated hoops to reduce weight to 17 tons. The breech mechanism was similar and loading two silk bags each containing 43 pounds of smokeless powder gave a 335-pound projectile a velocity of 2500 feet per second. Each gun could fire about four rounds per minute. Maximum range was at the maximum elevation of 41 degrees.

Mark 14

These guns were similar to Mark 9, with the same shell weight and maximum range, with a smaller chamber and rifling twist increased from 1 in 35 to 1 in 25 in a chromium-plated bore.

Mark 15

These guns were similar to Mark 12, with the same shell weight and maximum range, with the smaller chamber of the Mark 14 gun. Useful life expectancy was 715 effective full charges per liner.

Mark 16

These self-loading guns with lined monobloc construction and vertical sliding breech blocks weighed about 20 tons. Semi-fixed ammunition with 78 pounds of smokeless powder gave a 335-pound projectile a velocity of 2500 feet per second. Each gun could fire about ten rounds per minute. Useful life expectancy was 780 Effective Full Charges per liner. Range was 17 miles at the maximum elevation of 41 degrees. This gun was modified for the experimental Major Caliber Lightweight Gun.

Coast defense use

The eight twin turrets of and were removed in early 1942 during refits at Pearl Harbor. The turrets were turned over to the United States Army Coast Artillery Corps and remounted as coastal artillery on Oahu. Four two-turret batteries were established at Salt Lake near Aliamanu Crater, Wiliwilinui Ridge Military Reservation, Opaeula Military Reservation, and Brodie Camp Military Reservation. After the war, all of the guns and turrets were scrapped in 1948, along with almost all other US coast artillery.
One of s main battery 8 inch 55 caliber gun turrets damaged in a kamikaze attack on January 5, 1945, was removed and taken to the Nevada Test Site and converted into a rotating radiation detector, to collect data on nuclear tests.

Ships mounting 8"/55 caliber guns

  • 2 aircraft carriers:
  • *,
  • ** Mk 9 guns in four 190-ton twin turrets
  • ** removed in 1942 and added to Oahu coast defenses
  • 2 heavy cruisers:
  • *,
  • ** Mk 9 guns in two 190-ton twin turrets and two 250-ton triple turrets
  • 6 heavy cruisers:
  • * 2 of 6:,
  • ** Mk 9 guns in three 250-ton triple turrets
  • ** Houston was sunk in March 1942, Chicago was sunk in January 1943
  • * 4 of 6:,,,
  • ** Mk 9 guns in three 250-ton triple turrets
  • ** Northampton was sunk in November 1942
  • 2 heavy cruisers:
  • *,
  • ** Mk 9 guns in three 250-ton triple turrets
  • ** Indianapolis was sunk in July 1945
  • 7 heavy cruisers:
  • * 3 of 7: 294 ton triple turrets
  • ** : Mk 9 guns
  • ** : Mk 9 guns
  • ** : Mk 9 guns
  • ** Astoria was sunk in August of 1942
  • * 4 of 7:,,,
  • ** Mk 12 guns in three 250-ton triple turrets
  • ** Quincy and Vincennes were sunk in August 1942
  • * Mk 12 guns in three 314-ton triple turrets
  • 14 heavy cruisers:
  • * 1 of 14:
  • ** Mk 12 guns in three 300-ton triple turrets
  • * 13 of 14:,,,,,,,,,,,,
  • ** Mk 15 guns in three 300-ton triple turrets
  • 3 heavy cruisers:
  • *,,
  • ** Mk 15 guns in three 300-ton triple turrets
  • 3 heavy cruisers:
  • *,,
  • ** Mk 16 guns in three 450-ton triple turrets
  • 1 ex-:
  • * Mk 16 gun in one 86-ton single automatic mount 8"/55 caliber Mark 71 gun installation
ShipGun Installation
Mk 9 guns in four 190-ton twin turrets
Mk 9 guns in four 190-ton twin turrets
Mk 9 guns in two 190-ton twin turrets
and two 250-ton triple turrets
Mk 9 guns in two 190-ton twin turrets
and two 250-ton triple turrets
Mk 9 guns in three 250-ton triple turrets
Mk 9 guns in three 250-ton triple turrets
Mk 9 guns in three 250-ton triple turrets
Mk 9 guns in three 250-ton triple turrets
Mk 9 guns in three 250-ton triple turrets
Mk 9 guns in three 250-ton triple turrets
Mk 9 guns in three 294-ton triple turrets
Mk 9 guns in three 250-ton triple turrets
Mk 9 guns in three 294-ton triple turrets
Mk 9 guns in three 250-ton triple turrets
Mk 9 guns in three 294-ton triple turrets
Mk 12 guns in three 250-ton triple turrets
Mk 12 guns in three 250-ton triple turrets
Mk 12 guns in three 250-ton triple turrets
Mk 12 guns in three 250-ton triple turrets
Mk 12 guns in three 314-ton triple turrets
Mk 12 guns in three 300-ton triple turrets
CAG-1Mk 15 guns in three 300-ton triple turrets
CAG-2Mk 15 guns in three 300-ton triple turrets
Mk 15 guns in three 300-ton triple turrets
Mk 15 guns in three 300-ton triple turrets
Mk 15 guns in three 300-ton triple turrets
Mk 15 guns in three 300-ton triple turrets
Mk 15 guns in three 300-ton triple turrets
Mk 15 guns in three 300-ton triple turrets
Mk 15 guns in three 300-ton triple turrets
Mk 15 guns in three 300-ton triple turrets
Mk 15 guns in three 300-ton triple turrets
Mk 15 guns in three 300-ton triple turrets
Mk 15 guns in three 300-ton triple turrets
Mk 15 guns in three 300-ton triple turrets
Mk 16 guns in three 450-ton triple turrets
Mk 15 guns in three 300-ton triple turrets
Mk 15 guns in three 300-ton triple turrets
Mk 16 guns in three 450-ton triple turrets
Mk 16 guns in three 450-ton triple turrets
Mk 16 gun in one 86-ton single automatic mount

Weapons of comparable role, performance and era