16"/50 caliber Mark 7 gun

The 16"/50 caliber Mark 7 - United States Naval Gun is the main armament of the "Iowa"-class battleships. Due to its power and efficiency, it is sometimes considered to be one of the best battleship guns ever designed. [cite web
accessdate = 2007-11-21
format= html
url = http://www.navweaps.com/Weapons/WNUS_16-50_mk7.htm
title = 16"/50 (40.6 cm) Mark 7
date = 2007-09-17]

Due to a lack of communication in the design phase, the Bureau of Ordnance assumed the "Iowa" class would use the 16"/50 Mark 2 guns constructed for the 1920 "South Dakota"-class battleships. However, the Bureau of Construction and Repair assumed that the ships would carry a new, lighter, more compact 16"/50 and designed the ships with barbettes too small to accommodate a 16"/50 Mark 2 triple turret. The new 16"/50 Mark 7 was designed to resolve this conflict.

uper-heavy shell

The Mark 7 gun was originally intended to fire the relatively light 2,240 pound (1,016 kg) Mark 5 armor piercing shell. However, the shell handling system for these guns was redesigned to use the "super-heavy" 2,700 pound (1225 kg) APC (Armor Piercing, Capped) Mark 8 shell, before any of the "Iowa"-class battleships were laid down.

The "North Carolina" and "South Dakota" classes used the preceding 16"/45 caliber Mark 6 gun which could fire the same "super-heavy" 2,700 pound shell as the Mark 7. However, the Mark 6 had a significantly shorter range, though this was unlikely to have been a significant disadvantage in battleship combat. The Mark 6 gun was lighter, which helped both battleship classes to conform to the limits of the Washington Naval Treaty. [ [http://www.navweaps.com/Weapons/WNUS_16-45_mk6.htm USA 16"/45 (40.6 cm) Mark 6 ] ]

The heavier 2,700 pound projectiles made the Mark 7 guns nearly the equal in terms of penetration power to the 460 mm (18.1 in) guns of the Japanese "Yamato"-class battleships, although the guns were 25% lighter. The Mark 8 shells gave the "North Carolina", "South Dakota", and "Iowa" classes the heaviest broadside of all battleships, save for the "Yamato"-class super dreadnought, in spite of being treaty battleships.

The Mark 5 shells were a useful upgrade for the 16"/45 (40.6 cm) Mark 5 guns (formerly Mark 1 until reconstructed) of the "Colorado"-class battleships, compared to the original 2,110 lbs. (957.1 kg) AP Mark 3 shells.

The propellant consists of small cylindrical grains of smokeless powder with an extremely high burning rate. A maximum charge consists of six silk bags, each filled with 110 pounds of propellant. [ [http://query.nytimes.com/gst/fullpage.html?res=950DE1DE173DF930A15757C0A96F948260&sec=&spon=&pagewanted=all New York Times "Iowa Blast Inquiry: Long Search Ahead "] ]

Construction

The weapon is constructed of liner, tube, jacket, three hoops, two locking rings, tube and liner locking ring, yoke ring and screw box liner. Some components were autofretted. Typical of United States naval weapons built in the 1940s, the bore was chromium plated for longer barrel life. It uses a Welin breech block that opens downwards and is hydraulically operated. The screw box liner and breech plug are segmented with stepped screw threads arranged in fifteen sectors of 24 degrees each.

ee also

*List of artillery#Naval guns
*List of World War II artillery
*18.1"/45
*Armament of the Iowa class battleship

References

External links

* [http://www.navweaps.com/Weapons/WNUS_16-50_mk7.htm NavWeaps]