4-inch/50-caliber gun

4″/50 caliber gun Marks 7, 8, 9, and 10
4″/50 caliber gun Marks 7, 8, 9, and 10
	The gun from USS Ward which fired the first American shot of World War II at Pearl Harbor on 7 December 1941 at the State Capitol grounds in St. Paul, Minnesota.
Type	Naval gun
Place of origin	United States
Service history
In service	1898–1945
Used by	United States Navy; Royal Navy; Royal Canadian Navy; Soviet Navy;
Wars	World War I; World War II;
Production history
Designer	Bureau of Ordnance
Designed	Mark 7: 1898; Mark 8: 1905; Mark 9: 1914; Mark 10: 1914 (Did not enter service);
Manufacturer	U.S. Naval Gun Factory; Bethlehem Steel; Midvale Steel; British and American Mfg. Co.; Watervliet Arsenal; Root & VanDervoort; American Radiator Corp.; Poole Engineering;
No. built	Mark 7: 89; Mark 8: 12; Mark 9: 2,988; Mark 10: 1;
Variants	Mark 7, 8, 9 and 10
Specifications
Mass	Mark 7: 5,808 lb (2,634 kg) (with breech); Mark 8: 6,440 lb (2,920 kg) (with breech); Mark 9: 5,900 lb (2,700 kg) (with breech); Mark 10: 6,860 lb (3,110 kg) (with breech);
Length	Mark 7: 204.5 in (5,190 mm); Mark 8 and 9: 206.53 in (5,246 mm); Mark 10: 211 in (5,400 mm);
Barrel length	All: 200 in (5,080 mm) bore (50 calibres)
Shell	Fixed ammunition; 33 lb (15 kg) (projectile); 62.4–64.75 lb (28.30–29.37 kg) (complete round);
Calibre	4 in (102 mm)
Elevation	-15° to +20°
Traverse	-150° to 150°
Rate of fire	8-9 rounds per minute
Muzzle velocity	Mark 7: 2,500 ft/s (760 m/s); Mark 8: 2,800 ft/s (850 m/s); Mark 9 and 10: 2,900 ft/s (880 m/s);
Effective firing range	Mark 7: 9,000 yd (8,200 m) at 13° elevation
Maximum firing range	Mark 9: 15,920 yd (14,560 m) at 20° elevation

The 4″/50-caliber gun (spoken "four-inch-fifty-caliber") was the standard low-angle, quick-firing gun for the United States, first appearing on the monitor Arkansas and then used on "Flush Deck" destroyers through World War I and the 1920s. It was also the standard deck gun on S-class submarines, and was used to rearm numerous submarines built with 3-inch (76 mm) guns early in World War II. United States naval gun terminology indicates the gun fired a projectile 4 inches (10 centimeters) in diameter, and the barrel was 50 caliber. 4x50 meant that the barrel was 200 inches long, or 16 feet long .

4″/50 caliber gun Marks 7, 8, 9, and 10
The gun from USS Ward which fired the first American shot of World War II at Pearl Harbor on 7 December 1941 at the State Capitol grounds in St. Paul, Minnesota.
Type	Naval gun
Place of origin	United States
Service history
In service	1898–1945
Used by	United States Navy Royal Navy Royal Canadian Navy Soviet Navy
Wars	World War I World War II
Production history
Designer	Bureau of Ordnance
Designed	Mark 7: 1898 Mark 8: 1905 Mark 9: 1914 Mark 10: 1914 (Did not enter service)
Manufacturer	U.S. Naval Gun Factory Bethlehem Steel Midvale Steel British and American Mfg. Co. Watervliet Arsenal Root & VanDervoort American Radiator Corp. Poole Engineering
No. built	Mark 7: 89 Mark 8: 12 Mark 9: 2,988 Mark 10: 1
Variants	Mark 7, 8, 9 and 10
Specifications
Mass	Mark 7: 5,808 lb (2,634 kg) (with breech) Mark 8: 6,440 lb (2,920 kg) (with breech) Mark 9: 5,900 lb (2,700 kg) (with breech) Mark 10: 6,860 lb (3,110 kg) (with breech)
Length	Mark 7: 204.5 in (5,190 mm) Mark 8 and 9: 206.53 in (5,246 mm) Mark 10: 211 in (5,400 mm)
Barrel length	All: 200 in (5,080 mm) bore (50 calibres)

Shell	Fixed ammunition 33 lb (15 kg) (projectile) 62.4–64.75 lb (28.30–29.37 kg) (complete round)
Calibre	4 in (102 mm)
Elevation	-15° to +20°
Traverse	-150° to 150°
Rate of fire	8-9 rounds per minute
Muzzle velocity	Mark 7: 2,500 ft/s (760 m/s) Mark 8: 2,800 ft/s (850 m/s) Mark 9 and 10: 2,900 ft/s (880 m/s)
Effective firing range	Mark 7: 9,000 yd (8,200 m) at 13° elevation
Maximum firing range	Mark 9: 15,920 yd (14,560 m) at 20° elevation