View source for 3-inch/50-caliber gun

{{Infobox weapon
|name= 3-inch/50 caliber gun (Mk 22)
|image=File:Honolulu, HI, USA - panoramio.jpg
|caption=Mark 22 3"/50 cal gun
|origin= United States
|type= [[Naval gun]]
<!-- Type selection -->
|is_ranged=
|is_bladed=
|is_explosive=
|is_artillery= "yes"
|is_vehicle=
|is_UK=
<!-- Service history -->
|service=1900–1990 (US Navy)
|used_by= [[US Navy]]
|wars=
<!-- Production history -->
|designer=
|design_date=* '''Mark 2''': 1898<br>* '''Mark 10''': 1915<br>* '''Mark 22''': 1944
|manufacturer=
|production_date=1900–1948
|number=
|variants=Marks 2, 3, 5, 6, 8, 10, 17, 18, 19, 20, 21, and 22
<!-- General specifications -->
|weight=* '''Mark 2''': {{convert|2,086|lb|kg}} (with breech)
* '''Mark 21''': {{convert|1,760|lb|kg}}
|length=* '''Mark 2''': {{convert|153.8|in|m}}
* '''Mark 21''': {{convert|159.7|in|m}}
|part_length=* '''Mark 2''':  {{convert|150|in|cm}} bore (50 [[Caliber#Caliber as measurement of length|calibres]]) 
* '''Mark 21''': {{convert|150.3|in|cm}} bore (50 calibres)
|width=
|height=
|crew= 
<!-- Ranged weapon specifications -->
|cartridge= complete round: {{convert|24|lb|kg|abbr=on}};
projectile weight: {{convert|13|lb|kg|abbr=on}} projectile types: [[Armour-piercing shell|AP]], AA (with VT proximity fuze), HE, Illumination{{sfnm |1a1= DiGiulian, 3"/50 Marks 2–8 |2a1= DiGiulian, 3"/50 Marks 10–22 |3a1= DiGiulian, 3"/50 Marks 27–34 }}
|caliber= {{convert|3|in|mm|adj=on}}
|action=
|rate=*'''Mark 2''': 15 – 20 rounds per minute
*'''Mark 22''': 45 – 50 rounds per minute with autoloader<ref>Campbell 1985, p. 144</ref>
|velocity= {{convert|2700|ft/s|m/s|abbr=on}}
|range=
|max_range=* {{convert|14600|yd|abbr=on}} at 43° elevation
* {{convert|30400|ft|abbr=on}} [[anti-aircraft warfare|AA]] ceiling
|feed= SRF
|sights= Peep-site and Optical telescope
<!-- Artillery specifications -->
|breech=
|recoil=
|carriage=
|elevation=* '''Pedestal Mount''': -10° to +15° 
* '''AA Mount''': -10° to +85°
|traverse= 360°
<!-- Bladed weapon specifications -->
|blade_type=
|hilt_type=
|sheath_type=
|head_type=
|haft_type=
<!-- Explosive specifications -->
|diameter=
|filling=
|filling_weight=
|detonation=
|yield=
<!-- Vehicle specifications -->
|armour=
|primary_armament=
|secondary_armament=
|engine=
|engine_power=
|pw_ratio=
|suspension=
|vehicle_range=
|speed=
}}

The '''3-inch/50-caliber gun''' (spoken "three-inch fifty-caliber") in United States naval gun terminology indicates the gun fired a projectile {{convert|3|in}} in diameter, and the barrel was 50 [[Caliber (artillery)|caliber]]s long (barrel length is 3&nbsp;in × 50 = {{convert|150|in|m|abbr=on|disp=or|sigfig=2}}). Different guns (identified by Mark numbers) of this caliber were used by the [[U.S. Navy]] and [[U.S. Coast Guard]] from 1900 through to 1990 on a variety of combatant and transport ship classes.{{sfnm |1a1= DiGiulian, 3"/50 Marks 2–8 |2a1= DiGiulian, 3"/50 Marks 27–34}}

The gun is still in use with the [[Spanish Navy]] on [[Serviola-class patrol boat|''Serviola''-class patrol boats]].

==Early low-angle guns==
[[File:3-inch, 50 caliber gun, World War I.jpg|thumbnail|left|An early 3"/50 on {{USS|Rambler|SP-211}}, 1918.]]
[[Image:USSPivot3inchFiring.jpg|thumb|left|{{USS|Pivot|AM-276|6}} firing its forward 3"/50-caliber gun.]]

The US Navy's first 3 inch /50-caliber gun (Mark 2) was an early model with a projectile velocity of {{convert|2100|ft|m}} per second.  Low-angle (single-purpose/non-anti-aircraft) mountings for this gun had a range of 7000 yards at the maximum elevation of 15 degrees.  The gun entered service around 1900 with the {{sclass|Bainbridge|destroyer|1}}s, and was also fitted to {{sclass|Connecticut|battleship|1}}s.  By [[World War II]] these guns were found only on a few Coast Guard cutters and [[Defensively Equipped Merchant Ships]].{{sfn|Campbell|1985|p=146}}

Low-angle 3 inch/50-caliber guns (Marks 3, 5, 6, and 19) were originally mounted on ships built from the early 1900s through the early 1920s and were carried by submarines, auxiliaries, and merchant ships during the Second World War.  These guns fired the same {{convert|2700|ft/s|m/s|adj=on}} ammunition used by the following dual-purpose Marks, but with range limited by the maximum elevation of the mounting.  These were [[built-up gun]]s with a tube, partial-length jacket, hoop and vertical [[Rifled breech loader#The sliding block|sliding breech]] block.{{sfn|Campbell|1985|p=146}}

==Dual-purpose guns of the World Wars==
[[Image:Ld3inch.jpg|left|thumb|3"/50-caliber gun aboard {{USS|Slater|DE-766|6}}.]]
[[Dual purpose gun|Dual-purpose]] 3 inch/50-[[Caliber (artillery)|caliber]] guns (Marks 10, 17, 18, and 20) first entered service in 1915 as a refit to {{USS|Texas|BB-35}}, and were subsequently mounted on many types of ships as the need for anti-aircraft protection was recognized.  During World War II, they were the primary gun armament on [[destroyer escort]]s, [[patrol frigate]]s, [[submarine chaser]]s, [[minesweeper (ship)|minesweeper]]s, some fleet [[submarine]]s, and other auxiliary vessels, and were used as a secondary dual-purpose battery on some other types of ships, including some older battleships.  They also replaced the original low-angle [[4"/50 caliber gun|4"/50-caliber gun]]s (Mark 9) on "flush-deck" {{sclass|Wickes|destroyer|5}} and {{sclass|Clemson|destroyer|1}}s to provide better anti-aircraft protection.  The gun was also used on specialist destroyer conversions; the "AVD" [[seaplane tender]] conversions received two guns; the "APD" [[high-speed transport]]s, "DM" [[minelayer]]s, and [[Destroyer minesweeper|"DMS" minesweeper]] conversions received three guns, and those retaining destroyer classification received six.{{sfn|Silverstone|1968|pp= 112, 212, 215, 276, 303}}

These dual-purpose guns were "[[Quick-firing gun|quick-firing]]", meaning that they used fixed ammunition, with powder case and projectile permanently attached, and handled as a single unit weighing 34 pounds (as opposed to older guns and/or heavier guns, in which the shell and powder are handled and loaded separately, which reduces the weight of each handled component, but slows the loading process).  The [[Shell (projectile)|shells]] alone weighed about 13 pounds, including an explosive [[bursting charge]] of 0.81 pounds for [[anti-aircraft]] (AA) rounds or 1.27 pounds for high-capacity (HC) rounds, the remainder of the weight being the steel casing.  Maximum range was 14,600 yards at 45 degrees elevation and ceiling was {{convert|29800|ft|m}} at 85 degrees elevation.  Useful life expectancy was 4300 [[List of British ordnance terms#Effective Full Charge|effective full charge]]s (EFC) per barrel.{{sfn|Campbell|1985|p=145}}

This is not to be confused with the "rapid-fire" of later gun mounts that used an autoloader mechanism to insert the fixed QF ammunition into the breech. This in turn is not to be confused to a fully automatic gun. The autoloader was still manually filled with shells.

==Submarine deck guns==
The 3"/50-caliber gun Marks 17 and 18 was first used as a submarine [[deck gun]] on [[United States R-class submarine|R-class submarines]] launched in 1918–1919. At the time it was an improvement on the earlier [[3"/23 caliber gun|3"/23-caliber gun]].{{sfn|Gardiner|Gray|1985|p=130}} After using larger guns on many other submarines, the 3"/50-caliber gun Mark 21 was specified as the standard deck gun on the [[United States Porpoise-class submarine|''Porpoise'']]- through {{sclass|Gato|submarine|1}}s launched in 1935–1942. The small gun was chosen to remove the temptation to engage enemy escort vessels on the surface.{{sfn|Friedman|1995|p=193}} The gun was initially mounted aft of the [[conning tower]] to reduce submerged drag, but early in World War II it was shifted to a forward position at the commanding officer's option. Wartime experience showed that larger guns were needed. This need was initially met by transferring [[4"/50 caliber gun|4"/50-caliber gun]]s from [[United States S-class submarine|S-class submarines]] as they were shifted from combat to training roles beginning in late 1942. Later, the [[5"/25 caliber gun|5"/25-caliber gun]], initially removed from battleships sunk or damaged in the [[attack on Pearl Harbor]] and later manufactured in a submarine version, became standard.{{sfn|Friedman|1995|pp=214-219}}

==Cold War anti-aircraft gun==
[[File:Alva Laval Model 61 76mm gun.JPG|thumbnail|left|3-inch/50 Mk. 22 in Mk. 22 mounting in [[Aalborg Søfarts- og Marinemuseum|Aalborg Maritime Museum]].]]

During the final year of the [[Second World War]], it was found that multiple hits from [[Oerlikon 20 mm cannon]] and [[Bofors 40 mm Automatic Gun L/60|Bofors 40 mm gun]]s were often unable to shoot down high-speed Japanese [[kamikaze]] aircraft at short ranges before they hit Allied ships; the 3-inch/50-caliber gun was adopted as a more powerful replacement for these weapons.

[[File:3in50 Mk 33 mount on USS Wasp (CVA-18) c1954.jpg|upright|thumb|Mk. 33 twin mount on {{USS|Wasp|CV-18|6}}, in 1954.]]

The 3-inch/50-caliber gun (Mark 22) was a semiautomatic anti-aircraft weapon with a power-driven automatic loader and was fitted as single and twin mounts. The single mount was to be exchanged for a twin 40&nbsp;mm antiaircraft gun mount, and the twin 3-inch/50 for a quadruple 40&nbsp;mm mount, on {{sclass|Essex|aircraft carrier|1}}s, and {{sclass|Allen M. Sumner|destroyer|5}} and {{sclass|Gearing|destroyer|1}}s. Although intended as a one-for-one replacement for the 40&nbsp;mm mounts, the new {{convert|3|in|mm|adj=on}} mounts were heavier than expected, and on most ships, the mounts could only replace Bofors guns on a two-for-three basis. The mounts were of the dual purpose, open-base-ring type and the right and left gun assemblies were identical. The mounts used a common power drive that could train at a rate of 30 degrees/second and elevate from 15 degrees to 85 degrees at a rate of 24 degrees/second. The cannon was fed automatically from an on-mount magazine which was replenished by two loaders on each side of the cannon.<ref>{{Cite magazine |last= Brinkloe |first= W. D. |title= The Pouncer Challenges the Sub |magazine= [[Popular Mechanics]] |date= April 1955 |pages=88–93 |url= {{GBurl|y9wDAAAAMBAJ|p=90}} |access-date= 7 December 2020 }} See p. 90.</ref>

[[File:DN-ST-92-00268 twin 3inch 50cal gun mount.jpg|thumb|Mk.&nbsp;33 Mod.&nbsp;13 enclosed twin mount on {{USS|Blue Ridge|LCC-19|6}}, in 1991.]]
With [[proximity fuze]] and [[fire-control radar]], a twin 3-inch/50 mount firing 50 rounds per minute per barrel was considered more effective than a quad Bofors 40&nbsp;mm gun against subsonic aircraft,<ref>{{cite AV media |title= Photographic Report: The New Rapid Fire Naval Guns: 3"50 and 8"55 |date= c. 1949 |publisher= U.S. Navy, [[Naval Photographic Center]] |minutes= 8:41 |quote= YouTube title: USS Salem Rapid Fire Guns |via= YouTube user 'usssalemca139' |url= https://www.youtube.com/watch?v=ICifnf63lCs&t=521 | archive-url=https://ghostarchive.org/varchive/youtube/20211117/ICifnf63lCs| archive-date=2021-11-17 | url-status=live|access-date= 7 December 2020 }}{{cbignore}}</ref> but relatively ineffective against supersonic jets and [[cruise missile]]s. Destroyers that were modernized during the [[Fleet Rehabilitation and Modernization]] (FRAM) program of the 1960s had their {{convert|3|in|mm|adj=on}} guns removed. Experimentation with an extended range variant the fully automatic [[3"/70 Mark 26 gun]] was abandoned as shipboard [[surface-to-air missile]]s were developed. The United States Navy considered contemporary [[5-inch/38-caliber gun|5-inch/38-caliber guns]] and [[5-inch/54-caliber Mark 42 gun|5-inch/54-caliber Mark 42 guns]] more effective against surface targets.  In 1992, the 3-inch/50-caliber main battery on {{USCGC|Storis|WMEC-38|6}} was removed and was supposedly the last 3-inch/50-caliber gun in service aboard any US warship, although US Navy {{sclass|Charleston|amphibious cargo ship|1}}s retained their forward mounts until {{USS|El Paso|LKA-117}} was decommissioned in 1994.{{citation needed|date=October 2013}} The gun is still in service on warships of the [[Philippine Navy]].

The 17 {{sclass|Asheville|gunboat|1}}s mounted a single 3-inch/50 Mk 34 as their primary armament.

==Ships mounting 3-inch/50-caliber guns==

=== World War I ===
{{div col|colwidth=20em}}
* {{sclass|Bainbridge|destroyer|1}}s
* {{sclass|Chester|cruiser|1}}s
* {{sclass|Connecticut|battleship|1}}s
* {{sclass|Indiana|battleship|1}}s
* {{sclass|Mississippi|battleship|1}}s
* {{sclass|Nevada|battleship|1}}s
* {{sclass|New York|battleship|1}}s
* {{sclass|Paulding|destroyer|1}}s
* {{sclass|Pennsylvania|battleship|1}}s
* {{sclass|Pennsylvania|cruiser|1}}s
* [[United States R-class submarine|R-class submarines]]
* {{sclass|St. Louis|cruiser (1905)|0}} cruisers
* {{sclass|Smith|destroyer|1}}s
* {{sclass|South Carolina|battleship|1}}s
* {{sclass|Tennessee|cruiser|1}}s
* {{sclass|Truxtun|destroyer|1}}s
* {{sclass|Virginia|battleship|1}}s
{{div col end}}

=== World War II ===
<!--{{div col|colwidth=20em}}-->

The 3-inch/50 was standard-issue on at least 63 classes of ships that have a strong association with World War II.
The total number of vessels amounts to
** 10 light cruisers
** 119 submarines (est. maximum 119 installed)
** 498 destroyer escorts and frigates (1494 installed, 111 removed)
** 1110 patrol boats, mine sweepers and submarine chasers (1110 up to 1453 installed)
** 161 landing craft / amphibious assault ships (247 installed)
** 116+ auxiliaries (274 installed)

The submarines were built in the 1930s under the limitations of the [[Washington Naval Treaty]] and [[London Naval Treaty|its successors]] during a [[United States non-interventionism|period of isolationism]] and [[Great Depression|economic austerity]]. The division into classes was typically a result of construction during a particular fiscal year, but the number built each year was small.
The ''Gato''s became a mass-produced iteration of this line of research and development, because they coincided with the [[Two-Ocean Navy Act]].
Starting with the {{sclass|Balao|submarine|5}} class of submarines, the [[5-inch/25-caliber gun]] became the standard deck gun of the US Navy
** 2 {{sclass|Cachalot|submarine|5}} (FY33)
** 10 [[United States Porpoise-class submarine|''Porpoise'']] (FY34, FY35)
** 6 {{sclass|Salmon|submarine|5}} (FY36)
** 10 {{sclass|Sargo|submarine|5}} (FY37, FY38)
** 12 {{sclass|Tambor|submarine|5}} (FY39, FY40)
** 2 {{sclass|Mackerel|submarine|5}} (FY40)
** 77 {{sclass|Gato|submarine|5}} (FY41)

[[Destroyer escort]]s were a relative late-comer with production commencing in 1942 and were all mass-produced. They were quick to build and entered service in 1943. Later war-time classes had a main armament of two [[5-inch/38-caliber gun|5-inch/38]], [[High-speed transport|APD]] conversions had one such gun. Separation into classes is a result of different propulsion systems used and whether or not torpedoes were carried.
** 3 guns per vessel
** probably all manually loaded Mark 21 or Mark 22
** 65 {{sclass|Evarts|destroyer escort|5}} (diesel-electric, short hull, no torpedoes)
** 102 {{sclass|Buckley|destroyer escort|5}} (turbo-electric, 3 torpedoes)
*** 37 converted to APDs after commissioning, all 3-inch guns removed
** 72 {{sclass|Cannon|destroyer escort|5}} (diesel-electric, 3 torpedoes)
** 85 {{sclass|Edsall|destroyer escort|5}} (geared diesel, 3 torpedoes)
** 78 {{sclass|Captain|frigate}}s
*** 32 of 97 ''Evarts'' and 46 of 148 ''Buckley'' converted before commissioning, all 3-inch guns retained
** 75 {{sclass|Tacoma|frigate|1}}s (3 guns per ship)
*** essentially a destroyer escort with a merchant hull and triple expansion steam engines)
** 21 {{sclass|Colony|frigate|1}}s (3 guns per ship)
*** 21 of 96 ''Tacoma'' in Royal Navy service

Converted destroyers of the WW1-era {{sclass|Wickes|destroyer|5}} and {{sclass|Clemson|destroyer|5}} classes were equipped with 3-inch/50 guns while being converted to high speed transports (3 guns), minelayers (3), minesweepers (3) or seaplane tenders (2).

Patrol boats of less than 1000 tons, some of which were [[Wooden boats of World War II|wooden boats]]. These minesweepers were equipped with [[anti-submarine warfare]] equipment and their designs are closely related to the submarine chasers. Submarine chasers can be characterized as smaller, cheaper, coastal waters destroyer escorts. All ships in this group used diesel propulsion.
** 2 {{sclass|Raven|minesweeper|1}}s (1 per boat)
** 343 {{sclass|PC-461|submarine chaser|1}}s (1 or 2 per boat)
** 123 {{sclass|Admirable|minesweeper|1}}s (1 per boat)
** 68 {{sclass|PCE-842|patrol craft|1}}s (1 per boat
** 95 {{sclass|Auk|minesweeper|1}}s (1 per boat)
** 481 {{sclass|YMS-1|minesweeper|0}} [[Auxiliary motor minesweeper|yard minesweeper]]s (1 per boat)

Amphibious Assault Ships

** 130 [[Landing Craft Support]] (1 per vessel)
** [[Attack transport]]s
*** Based on pre-war cargo ships
**** 8 {{sclass|Harris|attack transport|0}} (4 per ship)
**** 2 {{sclass|McCawley|attack transport|0}} (4 per ship)
**** 5 {{sclass|Heywood|attack transport|0}} (4 per ship)
**** {{USS|John Penn|APA-23|3}} (4)
**** {{USS|Edward Rutledge|APA-24|3}} (1)
*** [[Type C3 ship]]
**** 7 {{sclass|President Jackson|attack transport|0}} (4 per ship)
**** 3 {{sclass|Arthur Middleton|attack transport|0}} (4 per ship)
**** 2 {{sclass|Frederick Funston|attack transport|0}} (2 per ship)
*** [[Type P1 ship]]
**** 2 {{sclass|Doyen|attack transport|0}} (4 per ship)

Auxiliary vessels, typically made of a cargo or tanker hull
** [[T1 tanker]]
*** 23 {{sclass|Patapsco|gasoline tanker}}s (4 per ship)
*** 34 {{sclass|Mettawee|gasoline tanker}}s (1 per ship)
** [[T2 tanker]]
*** 16 (geared turbine) {{sclass|Kennebec|oiler|1}}s (4 per ship)
*** 14 (turbo-electric) {{sclass|Suamico|oiler|1}}s (4 per ship)
*** 12 (turbo-electric) {{sclass|Escambia|oiler|1}}s (4 per ship)
** [[T3 tanker]]
*** 5 {{sclass|Chiwawa|oiler|1}}s (4 per ship)
*** 23 of 35 {{sclass|Cimarron|oiler|1||1939}}s (4 per ship)
** [[Type C1 ship|C1 Cargo]]
*** 63 {{sclass|Alamosa|cargo ship}}s (C1-M-AV1) (1 per ship)
** [[Type C2 ship|C2 Cargo]]
*** 7 {{sclass|La Salle|transport}}s (C2-S-B1) (4 per ship)
*** 2 {{sclass|Storm King|transport}}s (C2-S-AJ1) (4 per ship)
*** 8 {{sclass|Mount Hood|ammunition ship}}s (C2-S-AJ1) (4 per ship)
*** 7 {{sclass|Lassen|ammunition ship}}s (4 per ship)
** [[Type C3 ship|C3 Cargo]]
*** 4 {{sclass|Aegir|submarine tender}}s (4 per ship)
** [[Liberty Ship]]s
*** 18 {{sclass|Armadillo|tanker|1}}s (Z-ET1-S-C3) (1 per ship)
*** 48 of 65 {{sclass|Crater|cargo ship}}s (EC2-S-C1) (1 per ship)
*** 16 {{sclass|Guardian|radar picket ship}}s (Z-EC2-S-C5) (2 per ship)
*** 11 {{sclass|Acubens|stores ship}}s (EC2-S-C1) (1 per ship)
** 40 {{sclass|Ailanthus|net laying ship}}s (1 per ship)
** 15 {{sclass|Cohoes|net laying ship}}s (1 per ship)
** 32 {{sclass|Aloe|net laying ship}}s (1 per ship)
** 10 {{sclass|Portunus|motor boat tender}}s (1 per ship)
** 12 {{sclass|Aristaeus|repair ship}}s (1 per ship)
** 49 {{sclass|Sotoyomo|tugboat}}s (1 per boat)
** 29 {{sclass|Cherokee|tugboat|0}} fleet tugs (1 per boat)
** 27 {{sclass|Abnaki|tugboat|0}} fleet tugs (1 per boat)
** 17 {{sclass|Adria|stores ship}}s (1 per ship)
** 6 {{sclass|Mizar|stores ship}}s (3 or 4 per ship)
** 9 {{sclass|Chanticleer|submarine rescue ship}}s (2 per ship)
** 3 {{sclass|Penguin|submarine rescue ship}}s (1 per ship)
** 2 {{sclass|Pigeon|submarine rescue ship}}s (2 per ship)
** 4 {{sclass|Anchor|rescue and salvage ship}}s (1 per ship)
** 13 {{sclass|Cactus|buoy tender}}s (1 per ship)
** 6 {{sclass|Mesquite|buoy tender}}s (1 per ship)
** 20 {{sclass|Iris|buoy tender}}s (1 per ship)

'''Others'''
** {{sclass|Omaha|cruiser|1}}s (8 per ship, upgraded from 2)
*** the only vessels in the World War II category that had any armor.
** {{sclass|Treasury|cutter|1}}s
<!--{{div col end}}-->

=== Post–World War II ===
{{div col|colwidth=40em}}
'''Individual ships:'''
* {{USS|Bainbridge|CGN-25}} – built with 2 twin mounts{{sfn|Albrecht|1969|p=324}}
* {{HMCS|Bonaventure|CVL 22}} – built with 4 twin mounts, reduced to 2 during 1967 refit (Canada)
* {{USS|Juneau|CL-119}} – refit with 7 twin mounts{{efn|name=Juneau|All of the {{sclass|Juneau|cruiser|1}}s were planned for refit, but only ''Juneau'' was converted.{{sfn|Friedman|1984|p=242}} }}
* {{USS|Norfolk|DL-1}} – built with 4 twin mounts
* {{USS|Truxtun|CGN-35}} – built with 2 single mounts{{sfn|Albrecht|1969|p=324}}
* {{USS|Tulare|LKA-112}} – built with 6 twin mounts{{sfn|Blackman|1970|p=493}}

'''Ship classes:'''
* {{sclass|Allen M. Sumner|destroyer|1}}s – refit up to 6 guns
* {{sclass|Anchorage|dock landing ship|1}}s – built with 4 twin mounts{{sfn|Blackman|1970|p=497}}
* {{sclass|Annapolis|destroyer|1}}s – built with one Mark 33 twin mount forward (Canada)
* {{sclass|Asheville|gunboat|1}}s – built with a single mount
* {{sclass|Ashtabula|oiler|1}} – built with 4 single mounts{{sfn|Blackman|1970|p=521}}
* {{sclass|Austin|amphibious transport dock|1}}s – built with 4 twin mounts{{sfn|Blackman|1970|p=495}}
* {{sclass|Baltimore|cruiser|1}}s – refit up to 20 guns{{sfn|Albrecht|1969|pp=322-3}}
* {{sclass|Belknap|cruiser|1}}s – built with 2 single mounts{{sfn|Albrecht|1969|p=324}}
* {{sclass|Blue Ridge|command ship|1}}s – built with 4 twin mounts{{sfn|Blackman|1970|p=490}}
* {{sclass|Bronstein|frigate|1}}s – built with 1 twin and 1 single mount{{sfn|Blackman|1970|p=456}}
* {{sclass|Charleston|amphibious cargo ship|1}}s – built with 4 twin mounts{{sfn|Blackman|1970|p=493}}
* {{sclass|Claud Jones|destroyer escort|1}}s – built with 2 single mounts{{sfn|Blackman|1970|p=457}}
* {{sclass|De Soto County|tank landing ship|1}}s – built with 3 twin mounts{{sfn|Blackman|1970|p=499}}
* {{sclass|Dealey|destroyer escort|1}}s – built with 1 twin and 2 single mounts{{sfn|Albrecht|1969|p=327}}
* {{sclass|Denebola|stores ship|1}}s – built with 2 twin mounts{{sfn|Blackman|1970|p=519}}
* {{sclass|Des Moines|cruiser|1}}s – built with 10 twin mounts{{sfn|Albrecht|1969|p=320}}
* {{sclass|Essex|aircraft carrier|1}}s – refit up to 24 guns{{sfn|Friedman|1983|p=221}}
* {{sclass|Farragut|destroyer|1||1958}}s – built with 2 twin mounts{{sfn|Albrecht|1969|p=324}}{{efn|name=Coontz|The ''Farragut'' class is sometimes referred to as ''Coontz''-class, because the fourth ship of the class—USS ''Coontz'', designed ordered as a guided missile destroyer variant—was completed first.}}
* {{sclass|Fletcher|destroyer|1}}s – refit up to 6 guns
* {{sclass|Forrest Sherman|destroyer|1}}s – built with 2 twin mounts{{sfn|Albrecht|1969|p=325}}
* {{sclass|Gearing|destroyer|1}}s – refit up to 6 guns
* {{sclass|Guardian|radar picket ship|1}}s – converted from [[Liberty ship]]s with 2 single mounts{{sfn|Blackman|1970|p=520}}
* {{sclass|Iwo Jima|amphibious assault ship|1}}s – built with 4 twin mounts, some reduced to 2 mounts to provide space for missile launchers{{sfn|Blackman|1970|p=492}}
* {{sclass|Kilauea|ammunition ship|1}}s – built with 4 twin mounts{{sfn|Blackman|1970|p=518}}
* {{sclass|Leahy|cruiser|1}}s – built with 2 twin mounts{{sfn|Albrecht|1969|p=324}}
* {{sclass|Mackenzie|destroyer|1}}s – built with one Mark 33 twin mount aft except {{HMCS|Qu'Appelle|DDE 264|6}}, which received two Mark 33 twin mounts (one forward, one aft) (Canada)
* {{sclass|Mars|combat stores ship|1}}s – built with 4 twin mounts{{sfn|Blackman|1970|p=520}}
* {{sclass|Midway|aircraft carrier|1}}s – refit up to 40 guns{{sfn|Friedman|1983|p=221}}
* {{sclass|Neosho|fleet replenishment oiler|1}}s – built with 4 or 6 twin mounts{{sfn|Blackman|1970|p=520}}
* {{sclass|Newport|tank landing ship|1}}s – built with 2 twin mounts{{sfn|Blackman|1970|p=498}}
* {{sclass|Raleigh|amphibious transport dock|1}}s – built with 4 twin mounts{{sfn|Blackman|1970|p=496}}
* {{sclass|Restigouche|destroyer|1}}s – built with one Mark 33 twin mount aft, those refitted to the Improved ''Restigouche'' configuration had them removed (Canada)
* {{sclass|Rigel|stores ship|1}}s – built with 2 twin mounts{{sfn|Blackman|1970|p=519}}
* {{sclass|Sacramento|fast combat support ship|1}}s – built with 4 twin mounts{{sfn|Blackman|1970|p=522}}
* {{sclass|Simon Lake|submarine tender|1}}s – built with 2 twin mounts{{sfn|Blackman|1970|p=529}}
* {{sclass|St. Laurent|destroyer|1}}s – built originally with 2 Mark 33 twin mounts, later had one mount removed (Canada)
* {{sclass|Suribachi|ammunition ship|1}}s – built with 2 twin mounts{{sfn|Blackman|1970|p=518}}
* {{sclass|Terrebonne Parish|tank landing ship|1}}s – built with 3 twin mounts{{sfn|Blackman|1970|p=499}}
* {{sclass|Thomaston|dock landing ship|1}}s – built with 6 twin mounts{{sfn|Blackman|1970|p=497}}
* {{sclass|Wichita|replenishment oiler|1}}s – built with 4 twin mounts{{sfn|Blackman|1970|p=523}}
* {{sclass|Worcester|cruiser|1}}s – built with 2 single and 11 twin mounts{{sfn|Albrecht|1969|p=323}}
{{div col end}}

== Gallery ==
<gallery mode="nolines">
File:Cañón Mk.22 de 76 mm (3"-50) visto desde babor (16004573524).jpg|Single Mark&nbsp;22 aboard {{ship|Spanish patrol boat|Atalaya|P74|2}}.
File:3in guns on USS Austin (LPD-4) firing 1976.jpg|Twin Mark&nbsp;33 aboard {{USS|Austin|LPD-4|6}}.
File:Mk 33 twin-gun.jpg|Enclosed twin Mark&nbsp;33 Mod.&nbsp;13 aboard {{USS|Bronstein|FF-1037|6}}.
</gallery>

==Notes==
{{Notelist}}

==Footnotes==
{{Reflist|30em}}

== References ==
* {{cite book |last= Albrecht |first= Gerhard |date= 1969 |title= Weyer's Warships of the World 1969 |location= Annapolis, Maryland |publisher= Naval Institute Press }}
* {{cite book |last= Blackman |first= Raymond V. B. |date= 1970 |title= Jane's Fighting Ships 1970-71 |publisher=Jane's Yearbooks }}
* {{cite book |last= Campbell |first= John |date= 1985 |title= Naval Weapons of World War Two |location= Annapolis, Maryland |publisher= Naval Institute Press |isbn= 0-87021-459-4}}
* {{cite web |last= DiGiulian |first= Tony |date= 3 April 2020 |ref= {{sfnRef| DiGiulian, 3"/50 Marks 2–8}} |title= 3"/50 (7.62 cm) Marks 2, 3, 5, 6 and 8 |url= http://www.navweaps.com/Weapons/WNUS_3-50_mk2.php |access-date= 7 December 2020 |website= NavWeaps.com }}
* {{cite web |last= DiGiulian |first= Tony |date= 15 June 2016 |ref= {{sfnRef| DiGiulian, 3"/50 Marks 10–22}} |title= 3"/50 (7.62 cm) Mark 10, 17, 18, 19, 20, 21 and 22 |url= http://www.navweaps.com/Weapons/WNUS_3-50_mk10-22.php |access-date= 7 December 2020 |website= NavWeaps.com }}
* {{cite web |last= DiGiulian |first= Tony |date= 25 March 2019 |ref= {{sfnRef| DiGiulian, 3"/50 Marks 27–34}} |title= 3"/50 (7.62 cm) Marks 27, 33 and 34 |url= http://www.navweaps.com/Weapons/WNUS_3-50_mk27-33-34.php |access-date= 7 December 2020 |website= NavWeaps.com }}
* {{cite book |last= Friedman |first= Norman |date= 1983 |title= U.S. Aircraft Carriers: An Illustrated Design History |publisher= Naval Institute Press |location= Annapolis, Maryland |isbn= 0-87021-739-9 }}
* {{cite book |last= Friedman |first= Norman |date= 1984 |title= U.S. Cruisers: An Illustrated Design History |publisher= Naval Institute Press |location= Annapolis, Maryland |isbn= 0-87021-718-6 }}
* {{cite book |last= Friedman |first= Norman |date= 1995 |title= U.S. Submarines Through 1945: An Illustrated Design History |publisher= Naval Institute Press |location= Annapolis, Maryland |isbn= 1-55750-263-3 }}
* {{cite book |last1= Gardiner |first1= Robert |last2= Gray |first2= Randal |date= 1985 |title= Conway's All the World's Fighting Ships 1906-1921 |publisher= Conway Maritime Press |location= London |isbn= 0-85177-245-5 }}
*{{cite magazine |last1= Grulich |first1= Fred |date= 2004 |title= Question 37/00: Effectiveness of Shipboard Anti-Aircraft Fire |magazine= [[Warship International]] |publisher=International Naval Research Organization |volume= XLI |issue= 1 |pages= 31–33 |issn= 0043-0374 |ref=none }}
* {{cite book |last= Silverstone |first= Paul H. |date= 1968 |title= U.S. Warships of World War II |publisher= Doubleday and Company }}

== External links ==
* {{Commons-inline|list=
** [[commons:3inch/50 Marks 2 3 5 6 8 naval gun|3"/50 caliber naval gun, Marks 2, 3, 5, 6, 8]]
** [[commons:3inch/50 Marks 10-22 naval gun|3"/50 caliber naval gun, Marks 10–22]]
** [[commons:3inch/50 Marks 27 33 34 AA gun|3"/50 caliber naval gun, Marks 27, 33, 34]]
}}

{{WWIUSNavalWeapons}}
{{WWIIUSNavalWeapons}}

{{DEFAULTSORT:3 50 Caliber Gun}}
[[Category:76 mm artillery]]
[[Category:Naval anti-aircraft guns]]
[[Category:Naval guns of the United States]]
[[Category:World War I anti-aircraft guns]]
[[Category:World War I naval weapons]]
[[Category:World War II anti-aircraft guns]]
[[Category:World War II naval weapons]]