5"/51 caliber gun

• Name — 5"/51 caliber gun • Origin — United States • Type — * Naval gun • Coastal defence • Coast Guard gun • Is Ranged — yes • Is Artillery — yes • 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 • Designer — Bureau of Ordnance • Design Date — 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) • Number — * 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 • Weight — * Mark 7: (with breech) • Mark 8: (without breech) • Mark 8: (with breech) • Mark 9: (without breech) • Mark 9: (with breech) • Part Length — bore (51 calibers) • Rate — 8-9 rounds per minute • Velocity — * (full charge) • (reduced charge) • Range — at 20° elevation • Max Range — at 45° elevation (World War II ammunition) • 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

• Illustration — On a US Navy transport ship c. mid 1942 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 s, 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. A 1939 Table of Organization and Equipment shows Marine defense battalions were equipped with six of these guns each. 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 s 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: • Olympia - replacing 10 5"/40 and 4 8"/35 guns in 1917 • Chester - replacing 2 5"/50 and 4 3"/50 guns in 1917 • Birmingham - replacing 2 5"/50 and 4 3"/50 guns in 1917 • Salem - replacing 2 5"/50 and 4 3"/50 guns in 1917 • Florida • Utah • Wyoming • Arkansas • New York (Gun nos. 489–509) • Texas (Gun nos. 468–488) • Nevada • Oklahoma • Pennsylvania • Arizona • New Mexico • Mississippi • Idaho • Tennessee • California • Colorado • Maryland • West Virginia • Five s: • Hatfield • Brooks • Gilmer • * • Kane • Barracuda • Bass • Bonita • Langley • Long Island • Sangamon • Suwannee • Chenango • Santee • Charger • s • s • s • s (USCG Lake class cutters) • s

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. • 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

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. 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.

Surviving 5"/51 caliber guns include: • Eight guns on Olympia, preserved at the Independence Seaport Museum in Philadelphia, Pennsylvania (guns previously on Colorado) • Six guns preserved on Texas 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 Arizona and allegedly on Indiana 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 Idaho) • 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), at The 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

• BL 4.7-inch 45-calibre naval gun: British equivalent • 12 cm/45 3rd Year Type naval gun: Japanese equivalent • 120 mm 50 caliber Pattern 1905: Russian equivalent