Mark 16/1 triple 6 in /47 Turret

The Mark 16/1 triple 6-inch /47 gun turret (3x152 mm) was a feature of many U.S. cruisers during World War II. The Cleveland-class cruiser from that period had four such turrets.

Three 6 inch /47 Mark 16 guns were mounted as a triple turret

Today one of the few triple gun turrets left in the world is on the museum ship USS Little Rock (CG-4), which is located in the Buffalo and Erie County Naval & Military Park in Buffalo, New York.

6 inch /47 guns
Each gun could fire a 130 lb projectile 13 mi. Maximum range at 41 degrees elevation was 14.5 mi. Projectiles varied in weight; armor-piercing projectile weighed 130 pounds, a high capacity projectile weighed 105 pounds, and an anti-aircraft projectile weighed 65 pounds. Ammunition was semi-fixed (the projectile and the powder casing were separate). The powder case for these guns was housed in a brass canister and weighed 65 lb.

Eight to ten rounds per minute could be fired from each of the 6-inch guns. Each gun weighed 4.31 tons and could be elevated up to 60 degrees. Originally gun ports in the turret faces were cut to allow only 41 degrees elevation, though during World War Two all triple 6 inch/47 gun ports were ordered to be modified to permit the full 60 degrees. The guns could not be loaded at greater than 20 degrees elevation; this reduced the rate of fire when engaging distant surface targets or aircraft. All three guns in each turret were mounted in the same sleeve, but delay coils permitted "split salvos" to be fired; this cured a shell pattern dispersion problem common to many US cruisers of the 1920s and 1930s. The 105 pound armor piercing shell fired at 2810 feet per second could pierce up to 5 in (127 mm) of hardened armor plate out to 9,200 yards; the 130 pound AP shell introduced just before World War Two fired at 2500 feet per second could penetrate out to 15,700 yards.

Gun barrel lives were 750 to 1050 full charge rounds.

Design
A 6-inch triple turret weighed in at about 70 tons, and each rifle barrel was 23 ft long. The turret rested on a barbette or circular shaft that extended several decks into the ship. Projectiles were stored in a projectile handling room in the lower part of the barbette. Over 900 projectiles could be stored in the projectile handling room. The guns were supplied with projectiles via hoists.

Powder stores were below the projectile handling room and powder hoists fed the guns. Empty powder canisters were ejected from the turret via an ejector port at the back of the turret. When the guns were firing, it was not unusual to see empty brass canisters piling up on the deck behind the turret. The turret itself had 6.5 in of armor plate on its face and could train (turn) to follow its target at ten degrees a second.

Each turret required a crew of 3 officers and 52 enlisted men.

Deployment
As well as ships of the Cleveland-class cruiser, these turrets were also fitted to the Brooklyn-class cruiser, St. Louis, and Fargo-class cruiser class cruisers.