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5-inch/51-caliber gun

20th-century naval gun of the United States Navy

5"/51 caliber gun
5"/51 caliber Mark 8 gun on starboard forecastle of USS Texas, March 1914
Type	Naval gun Coastal defence Coast Guard gun
Place of origin	United States
Service history
In service	1911–c. 1947
Used by	United States Navy United States Marine Corps United States Coast Guard Royal Navy
Wars	World War I World War II
Production history
Designer	Bureau of Ordnance
Designed	1910
Manufacturer	Naval Gun Factory American & British Mfg. Co. (Nos. 702–727) Watervliet Arsenal (Nos. 768–787) Liberty Ordnance Co. (Nos. 898–1043) Four Lakes Ordnance Co. (Nos. 1157–1356) Midvale Steel (Nos. 1457–1504 and 1705–1716) American Can Co. (Nos. 1505–1518)
No. built	Mark 7: 93 (Nos. 357–449) Mark 8: 1004 (NGF 539 Nos. 450-unknown)(see builders) (No Nos. 1357–1456, 1519–1604 or 1633–1704) Mark 9: 3 (Unknown Nos.) Mark 14: relined Mark 8s Mark 15: enlarged chamber Mark 14s
Variants	Marks 7, 8, 9, 14, 15
Specifications
Mass	Mark 7: 11,274 lb (5,114 kg) (with breech) Mark 8: 10,834 lb (4,914 kg) (without breech) Mark 8: 11,300 lb (5,100 kg) (with breech) Mark 9: 10,824 lb (4,910 kg) (without breech) Mark 9: 11,375 lb (5,160 kg) (with breech)
Length	261.25 in (6,636 mm)
Barrel length	255 in (6,500 mm) bore (51calibers)
Shell	50–55.18 lb (22.68–25.03 kg)
Caliber	5 in (127 mm)
Breech	side swing Welin-type
Elevation	P13: -10° to +20° (late version) P15: -15° to +20° Mark 18: -8.5° to +25°
Traverse	up to 360° depending on location
Rate of fire	8-9 rounds per minute
Muzzle velocity	3,150 ft/s (960 m/s) (full charge) 2,300 ft/s (700 m/s) (reduced charge)
Effective firing range	17,000 yd (16,000 m) at 20° elevation
Maximum firing range	20,142 yd (18,418 m) at 45° elevation (World War II ammunition)

5"/51 caliber guns (spoken "five-inch-fifty-one-caliber") initially served as the secondary battery of United States Navy battleships built from 1907 through the 1920s, also serving on other vessels. United States naval gun terminology indicates the gun fired a projectile 5-inch (127 mm) in diameter, and the barrel was 51 calibers long.^[1]

Description[edit]

The different marks of the gun were Marks 7, 8, 9, 14, and 15. The built-up gun consisted of a tube, full-length jacket, and single hoop with side swing Welin breech block and Smith-Asbury mechanism for a total weight of about 5 metric tons. Some Marks included a tapered liner. A 24.5 lb (11.1 kg) charge of smokeless powder gave a 50-pound (23 kg) projectile a velocity of 3,150 ft/s (960 m/s). Range was 15,850 yards (9.0 statute miles or 14.5 kilometres) at the maximum elevation of 20 degrees.^[2] Useful life expectancy was 900 effective full charges (EFC) per liner.^[3]

US service[edit]

The 5-inch/51 caliber gun was designed to engage destroyers, torpedo boats, and other surface targets. The 5"/51 gun entered service in 1911 as secondary armament on the Florida-class battleships, which mounted 16. The guns served well through World War I, but increased awareness of the need for anti-aircraft protection (especially following the attack on Pearl Harbor) encouraged mounting of dual-purpose 5"/38 caliber guns in later battleships, and some of the World War I-era battleships were rearmed with dual purpose guns as well. Surplus 5"/51 guns from scrapped or rearmed battleships were mounted in United States Coast Guard cutters, auxiliaries, small aircraft carriers, coast defense batteries, and Defensively Equipped Merchant Ships.^[3] A 1939 Table of Organization and Equipment shows Marine defense battalions were equipped with six of these guns each.^[4] 5-inch/51 shore batteries were used with great effectiveness by the 1st Marine Defense Battalion during the Battle of Wake Island in December 1941. These were replaced in the defense battalions by the 155 mm Long Tom gun by 1943. Six Tambor-class submarines were rearmed with "wet mount" 5-inch/51 guns during World War II, taken from Barracuda-class submarines or spares for that class.

The 5"/51 caliber gun was mounted on:

Army coast defense use[edit]

5"/51 caliber ex-Navy guns were emplaced during World War II at several locations, some operated by the United States Army Coast Artillery Corps and some by Marine defense battalions. This list may not be exhaustive. They were grouped into two-gun batteries unless otherwise noted.^[25]

• Two guns near Cape Lookout, NC
• Three guns in Battery Gillespie, Point Loma, San Diego, CA
• Three guns in Battery Ahua, Fort Kamehameha, Oahu, HI
• Two guns in Battery Nanakuli, Oahu, HI
• Two guns in Battery Oneula (Ewa), Oahu, HI
• Two guns at Kahana Bay, North Shore, Oahu, HI

British service[edit]

In British service these guns were known as 5"/51 BL Mark VI and Mark VII. During World War I three of these guns formed part of the coastal defences of Scapa Flow.^[2] In World War II a small number of these guns entered British service on board ships transferred under the Lend-Lease arrangement. Some of these guns were then transferred to New Zealand (at least six, possibly more) and deployed ashore for coastal defence.^[2]

Surviving examples[edit]

Surviving 5"/51 caliber guns include:^[26]

• Eight guns on USS Olympia (C-6), preserved at the Independence Seaport Museum in Philadelphia, Pennsylvania (guns previously on USS Colorado (BB-45))
• Six guns preserved on USS Texas (BB-35) near Houston, Texas
• One Mark 8 gun (Four Lakes #1205) at Trumbo Point, Key West, Florida (part of Naval Air Station Key West)
• One gun (Unk. mfr. #1093L2) at the Ropkey Armor Museum, Crawfordsville, Indiana (previously on USS Arizona (BB-39) and allegedly on USS Indiana (BB-1) at some time)
• Two Mark 7 guns (Watervliet #774 and #Unk.) on Midway Island, Central Pacific Ocean
• One Mark 7 gun (Naval Gun Factory (NGF) #415L) at the NROTC facility, Tulane University, New Orleans, Louisiana
• One Mark 15 gun (NGF #736L) at the U.S. Navy Museum, Washington Navy Yard, Washington, DC (previously on USS Idaho (BB-42))
• One 5"/51 caliber gun at Fort Schuyler, Bronx, New York (possibly at USMMA, Kings Point, New York)
• One 5"/51 caliber gun at Treasure Island, San Francisco, California (behind museum)
• One Mark 15 gun in Lewiston, Maine
• One Mark 15 gun (Bethlehem #Unk.) at the Brunswick Executive Airport, Brunswick, Maine (formerly NAS Brunswick)
• One 5"/51 caliber gun in Mitchell, Indiana
• One Mark 9 Mod 3 gun (NGF #938L), American Military Museum, South El Monte, California
• One 5"/51 caliber gun at the Veterans Memorial Museum, Chehalis, WA
• Two 5"/51 caliber guns at the Veterans Memorial in Haddon Heights, NJ

See also[edit]

Weapons of comparable role, performance and era[edit]

• BL 4.7-inch 45-calibre naval gun : British equivalent
• 12 cm/45 3rd Year Type naval gun : Japanese equivalent

Notes[edit]

References[edit]

• Bauer, K. Jack; Roberts, Stephen S. (1991). Register of Ships of the U.S. Navy, 1775-1990: Major Combatants. Westport, Connecticut: Greenwood Press. ISBN 0-313-26202-0.
• Berhow, Mark A., ed. (2015). American Seacoast Defenses, A Reference Guide (Third ed.). McLean, Virginia: CDSG Press. ISBN 978-0-9748167-3-9.
• Breyer, Siegfried (1973). Battleships and Battlecruisers 1905–1970. Doubleday and Company. ISBN 0-385-07247-3.
• Campbell, John (1985). Naval Weapons of World War Two. Naval Institute Press. ISBN 0-87021-459-4.
• Fahey, James C. (1939). The Ships and Aircraft of the U.S. Fleet. Ships and Aircraft.
• Fahey, James C. (1941). The Ships and Aircraft of the U.S. Fleet, Two-Ocean Fleet Edition. Ships and Aircraft.
• Fairfield, A.P. (1921). Naval Ordnance. The Lord Baltimore Press.
• Friedman, Norman (1983). U.S. Aircraft Carriers. Naval Institute Press. ISBN 0-87021-739-9.
• Preston, Antony (1980). Cruisers. Prentice Hall. p. 60. ISBN 0-13-194902-0.
• Friedman, Norman (2011). Naval Weapons of World War One. Seaforth Publishing. ISBN 978-1-84832-100-7.

External links[edit]

• List of all US coastal forts and batteries at the Coast Defense Study Group, Inc. website
• FortWiki, lists most CONUS and Canadian forts