View source for 5-inch/38-caliber gun

{{Use dmy dates|date=June 2017}}
{{Infobox weapon
|name= 5"/38 caliber gun
|image=Forward gun turrets of USS David W. Taylor (DD-551) at Hunters Point Naval Shipyard, California (USA), on 23 April 1945.jpg
|image_size=300
|caption= Two Mk 30 single enclosed base ring mounts on {{USS|David W. Taylor|DD-551|6}}
|origin= United States
|type= Deck gun
<!-- Type selection -->
|is_artillery=yes
<!-- Service history -->
|service= 1934–2008
|used_by= [[United States Navy]], [[United States Coast Guard]], [[Royal Navy]], [[Danish Navy]], [[Italian Navy]], [[Japan Maritime Self-Defense Force]], [[South Vietnamese Navy]], and every navy that bought surplus World War II, US Navy warships
|wars= [[World War II]], [[Korean War]], [[Vietnam War]], [[Gulf War]], [[Falklands War]], and wars that involved navies who bought surplus World War II, US Navy warships
<!-- Production history -->
|designer=
|design_date= 1931–1932
|manufacturer=
|production_date=
|number=
|variants=
<!-- General specifications -->
|weight= Mk 12 Gun Assembly: {{convert|3990|lb|kg|abbr=on}}. Mounts varied from {{convert|29260|lb|kg|abbr=on}} to {{convert|170653|lb|kg|abbr=on}}
|length= Mk 12 Gun Assembly: {{convert|223.8|in|m|2|abbr=on}}
|part_length= {{convert|190|in|m|abbr=on|2}} bore, {{convert|157.2|in|m|abbr=on|2}} rifling
|width=
|height=
|crew= Varied on mount type
<!-- Ranged weapon specifications -->
|cartridge=127×680mmR<ref>{{cite web | url=https://www.quarryhs.co.uk/ammotable12.html | title=106 | access-date=13 October 2022 | archive-date=7 December 2021 | archive-url=https://web.archive.org/web/20211207120743/https://www.quarryhs.co.uk/ammotable12.html | url-status=dead }}</ref><br> {{convert|53|to|55|lb|kg|abbr=on}}
|caliber= {{convert|5|in|mm|abbr=on|0}}
|action=
|rate= Design: 15 rpm
|velocity= {{convert|2600|ft/s|abbr=on}} initial
|range=
|max_range=
|feed=
|sights= Optical telescope
<!-- Artillery specifications -->
|breech= Vertical [[Rifled breech loader#The sliding block|sliding-wedge]]
|recoil= {{convert|15|in|cm|abbr=on}}
|carriage=
|elevation= −15° to +85°
|traverse= 328.5 degrees
}}
The '''Mark 12 5"/38-caliber gun''' was a United States [[dual purpose gun|dual-purpose]] [[Naval artillery|naval gun]], but also installed in single-purpose mounts on a handful of ships. The 38-[[Caliber (artillery)|caliber]] barrel was a mid-length compromise between the previous United States standard [[5"/51 caliber gun|5"/51 low-angle gun]] and [[5-inch/25-caliber gun|5"/25 anti-aircraft gun]]. United States naval gun terminology indicates the gun fired a projectile {{convert|5|in|mm|0}} in diameter, and the barrel was 38&nbsp;[[Caliber (artillery)|calibers]] long. The increased barrel length provided greatly improved performance in both anti-aircraft and anti-surface roles compared to the 5"/25 gun. However, except for the barrel length and the use of [[Shell (projectile)#Separate loading cased charge|semi-fixed]] ammunition, the 5"/38 gun was derived from the 5"/25 gun. Both weapons had power ramming, which enabled rapid fire at high angles against aircraft. The 5"/38 entered service on {{USS|Farragut|DD-348|6}}, commissioned in 1934, the first new destroyer design since the last ''Clemson'' was built in 1922. The base ring mount, which improved the effective [[rate of fire]], entered service on {{USS|Porter|DD-356|6}}, commissioned in 1936.<ref name="5/38">{{Cite web |url=http://www.navweaps.com/Weapons/WNUS_5-38_mk12.php |title=United States of America 5"/38 (12.7 cm) Mark 12 |last=DiGiulian |first=Tony |access-date=2 March 2018 |date=February 2013 |publisher=navweaps.com}}</ref><ref >{{USS|Gridley|DD-380|2}} (June 1937) marks the introduction of the base ring mount in the main line of destroyers. The last 2 ''Mahan'' class ships also had them, {{USS|Dunlap|DD-384|2}} was commissioned in June 1937, too. Porter entered service much sooner</ref>
Among naval historians, the 5"/38 gun is considered the best intermediate-caliber,<ref>a Bore diameter greater than {{convert|4|in|mm|0}} and less than {{convert|8|in|mm|0}}.</ref> dual purpose naval gun of World War II,<ref name="NavOrdAndGunV1"/> especially as it was usually under the control of the advanced [[Mark 37 Gun Fire Control System]] which provided accurate and timely firing against surface and air targets. Even this advanced system required nearly 1000&nbsp;rounds of ammunition expenditure per aircraft kill.<ref>Naval Weapons of WW2, Campbell, P106</ref> However, the planes were normally killed by shell fragments and not direct hits; barrage fire was used, with many guns firing in the air at the same time. This would result in large walls of shell fragments being put up to take out one or several planes or in anticipation of an unseen plane, this being justifiable as one plane was capable of significant destruction. The comparatively high rate of fire for a gun of its caliber earned it an enviable reputation, particularly as an anti-aircraft weapon, in which role it was commonly employed by [[United States Navy]] vessels. Base ring mounts with integral hoists had a nominal rate of fire of 15&nbsp;rounds per minute per barrel; however, with a well-trained crew, 22 rounds per minute per barrel was possible for short periods.<ref name="NavOrdAndGunV1">{{Cite book |title=Naval Ordnance And Gunnery, Volume 1, Naval Ordnance, NAVPERS 10797-A |publisher=U.S. Navy, Bureau of Naval Personnel |year=1957 |edition=1957 |location=Washington, D.C.}}</ref> On pedestal and other mounts lacking integral hoists, 12 to 15 rounds per minute was the rate of fire.<ref>{{Cite web |url=http://www.navweaps.com/Weapons/WNUS_5-38_mk12.php |title=United States of America 5"/38 (127 mm) Mark 12 |last=DiGiulian |first=Tony |access-date=2 March 2018 |date=November 2006 |publisher=navweaps.com |quote=Pedestal and other mounts lacking integral hoists: 12{{spaced en dash}} 15 rounds per minute}}</ref> Useful life expectancy was 4600 [[List of British ordnance terms#Effective Full Charge|effective full charges]] (EFC) per barrel.<ref>Naval Weapons of WW2, Campbell, P139</ref>
The 5"/38 cal gun was mounted on a very large number of US Navy ships in the [[World War II]] era. It was backfitted to many of the [[World War I]]-era battleships during their wartime refits, usually replacing 5"/25 guns that were fitted in the 1930s. It has left active US Navy service, but it is still on mothballed ships of the [[United States Navy reserve fleets]]. It is also used by a number of nations who bought or were given US Navy surplus ships. Millions of rounds of ammunition were produced for these guns, with over 720,000 rounds still remaining in Navy storage depots in the mid-1980s because of the large number of Reserve Fleet ships with 5"/38 cal guns on board.
==Mark 12 5"/38 cal gun assembly==
[[File:Mk12 5in Gun Assembly.jpg|left|thumb|Mk 12 gun assembly]]
Each mount carries one or two '''Mk 12 5"/38cal Gun Assemblies'''. The gun assembly shown is used in single mounts, and it is the right gun in twin mounts. It is loaded from the left side. The left gun in twin mounts is the mirror image of the right gun, and it is loaded from the right side. The Mk12 gun assembly weighs {{convert|3990|lb|kg|abbr=on}}.<ref name="5/38"/> The Mark&nbsp;12 Gun Assembly was introduced in 1934, where it was first used in single pedestal mounts on the {{sclass|Farragut|destroyer|2||1934}}s,<ref>{{Cite web |url=http://www.navweaps.com/Weapons/WNUS_5-38_mk12.php |title=United States of America 5"/38 (12.7 cm) Mark 12 |last=DiGiulian |first=Tony |access-date=2 March 2018 |date=November 2006 |publisher=navweaps.com |quote=The earliest mountings as [sic] used on USS Farragut (DD-348) were pedestal mounts with shell and cartridge hoists located on the deck behind the gun mount.}}</ref> but by the time of World War II they had been installed in single and twin mounts on nearly every major warship and auxiliary in the US fleet.<ref name="5/38"/>
{{clear}}
===Characteristics===
The major '''Mk12 Gun Assembly''' characteristics are:{{r|NavOrdAndGunV1|page=158}}<ref name="5/38"/>
;Semi-automatic
:During recoil, some of the recoil energy is stored in the counter-recoil system. That stored energy is used during counter-recoil to prepare the gun for the next round. The firing pin is cocked, the breech is opened, the spent propellant case is ejected, and the bore is cleared of debris with an air blast.
;Hand loaded
:A projectile-man and a powder-man are stationed at each gun assembly. Their job is to move the round, consisting of a projectile and a propellant case, from the hoists to the rammer tray projecting from the gun's breech, and then start the ram cycle. The powder case is placed first and the projectile rests against the powder case.
[[File:VrtclSldngWdgBrchBlck.jpg|right|thumb|Vertical Sliding Wedge Breech Block.]]
;Power rammed
:This gun used a {{convert|7.5|hp|abbr=on|adj=on}} electric-hydraulic power rammer that was designed to ram a {{convert|93|lb|kg|adj=on}}, {{convert|47.5|in|m|abbr=on|adj=mid|-long}} round (combined weight of projectile and propellant) into the chamber at any gun elevation in less than one second.{{r|NavOrdAndGunV1|page=172}} The rammer's control box, hydraulic fluid tank and AC motor are bolted to the top of the slide (''see the Gun Assembly picture above''). The hydraulically driven rammer spade, called the power spade in that picture, is at the back of the rammer tray. If the multiple names of the "spade" are confusing, look at this footnote.<ref>What this article calls the "rammer spade" is called the "power spade" in the gun assembly picture, and is parenthetically called the "shell guard" in the rammer tray illustration. This is probably the result of different Navy documents written by different people at different times. Ultimately, it became the "rammer spade" as shown in the rammer tray illustration. This is because it looked like a small, leather-covered garden spade—and it was what rammed the round into the chamber.</ref> Hand ramming was also possible in case of power failures with rate of fire approximately cut in half.<ref>{{cite web |title=Action Report: 24 August 1942 |url=http://www.cv6.org/ship/logs/action19420824.htm |website=cv6.org |access-date=1 July 2022}}</ref>
;Vertical sliding-wedge breech block (see drawing)
:The breech block closes the chamber behind the propellant case. It also contains the firing pin assembly.
;Hydraulic recoil
:Two hydraulic pistons in the housing absorb the major shock of recoil as the housing moves back inside the slide (''see picture''). They also buffer the end of counter-recoil for a soft return to battery.
[[File:5in38calReclSystDrw.jpg|right|thumb|Drawing of the recoil and counter-recoil systems. The arrow shows the motion of the housing in the slide during recoil.]]
;Pneumatic counter-recoil
:At the end of recoil, the counter-recoil system moves the housing forward again until it is back "in battery," and holds it there at any gun elevation. A chamber in the housing is filled with compressed air. At the rear of this chamber is a {{convert|3.5|in|cm|abbr=on|adj=on}} cylindrical hole with a chevron packing. {{r|NavOrdAndGunV1|page=161}} Projecting through the hole is a movable piston that abuts the back of the slide (''see picture''). The air pressure in the chamber attempts to push the piston out of the chamber, but the piston can't move because of the slide. Therefore, since the piston can't go backwards, the air pressure in the chamber forces the housing forward. When the gun is in battery, the pressure in this chamber is about {{convert|1500|psi|MPa|abbr=on}}. During recoil, the pressure rises to about {{convert|2250|psi|MPa|abbr=on}}.{{r|NavOrdAndGunV1|page=162}}
;Barrel designation ('''5"/38 Caliber'''):
* '''5"''' is the caliber of this gun. The term "caliber" used here is the [[Caliber (artillery)|artillery caliber]] definition, and its value is equal to the bore diameter as measured from land to land.{{r|NavOrdAndGunV1|page=81}} Lands are the raised portions of the bore rifling, between the grooves.{{r|NavOrdAndGunV1|page=81}} (note: artillery caliber and [[Caliber|small arms caliber]] are not the same).
* '''38 caliber''' means that the barrel from breech face to muzzle is 38 calibers in length.{{r|NavOrdAndGunV1|page=81}} As this gun's caliber is 5 inches (127mm), its barrel length is 38 times 5 inches: {{convert|190|in|cm ft}}.
;Barrel description {{r|NavOrdAndGunV1|page=160}}:
* Radially expanded monobloc steel alloy.
* Weight: {{convert|2000|lb|kg|abbr=off}}
* The bore is chrome plated from the origin of rifling (forward end of the chamber) to the muzzle.
* 45&nbsp;groove rifling with a full uniform right hand twist in 30 Calibers ({{convert|150|in|cm|abbr=off}}).
* Maximum bore pressure of a new gun firing an anti-aircraft common projectile: {{convert|40320|psi|abbr=off}}. {{r|NavOrdAndGunV1|page=34}}
* Barrel connected to the housing with a bayonet joint that allowed for its replacement by [[destroyer tender]]s in the theater of operation, without dismantling the breech mechanism or other parts.<ref name="5/38"/>
;Ballistics: Maximum horizontal range with a {{convert|55|lb|kg|adj=on}} projectile is {{convert|18000|yd|m}}.{{r|NavOrdAndGunV1|page=159}} In the anti-aircraft role, the gun has a ceiling of {{convert|37,200|ft|m}} at 85 degrees elevation.{{r|NavOrdAndGunV1|page=159}}
;Armor penetration with {{convert|54|lb|kg|adj=on}} special common shell{{r|5/38}}:
:5.0" (127 mm) belt armor at {{convert|4,000|yd|m}}
:4.0" (102 mm) at {{convert|5,400|yd|m}}
:3.0" (76 mm) at {{convert|7,400|yd|m}}
:2.0" (51 mm) at {{convert|11,000|yd|m}}
:1.0" (25 mm) deck armor at {{convert|13,800|yd|m}}
:with {{convert|55.18|lb|kg}} AA common shell: {{convert|1.5|in|mm}} at {{convert|10,000|yd|m}}
;Range with {{convert|55.18|lb|kg|adj=on}} AAC Mark 49 (792 mps){{r|5/38}}:
:10° {{convert|9,506|yd|m}}
:15° {{convert|11,663|yd|m}}
:20° {{convert|13,395|yd|m}}
:25° {{convert|14,804|yd|m}}
:30° {{convert|15,919|yd|m}}
:35° {{convert|16,739|yd|m}}
:40° {{convert|17,240|yd|m}}
:45° {{convert|17,392|yd|m}}
:AA Ceiling {{convert|37,200|ft}}
The new gun initial [[muzzle velocity]] is {{convert|2600|ft/s|m/s|abbr=off}}, and the gun life average initial muzzle velocity is about {{convert|2500|ft/s|m/s|abbr=off}}{{r|5/38}}.
US ships during World War II carried only small quantities of special common ammunition, as the anti-aircraft common was considered more useful, even if it meant achieving much less armor penetration.{{r|5/38}} Bursting charges were {{convert|7.25|lb}} explosive D composition A, the special common had only 0.9-1.2&nbsp;kg due to its thicker walls (AP).{{r|5/38}}
===Loading===
At the "LOAD" command, or if the mount is executing "RAPID" loading: (NOTE: Rapid loading means that, when the gun fires, the gun crew immediately reloads the gun without command until "CEASE FIRE" or "CHECK FIRE" is given.)<ref name="GM3">{{cite book |title=Gunner's Mate 3, Vol. 1, NAVPERS 10158-A |publisher=US GPO |date=1952 |location=Washington, DC}}</ref>
[[File:5in38calRmmrTry.jpg|right|thumb|Rammer Tray with Powder Case and Projectile ready for ramming.]]
The Powder-Man:{{r|NavOrdAndGunV1|page=175}}
# Verifies that the '''RAMMER SPADE''' is at the rear of the "Rammer Tray" (''see picture'')
# Slips the "Butterfly" primer protector off the base of the powder case that is sticking knee high out of powder hoist on the deck.
# Throws the protector out of the mount.
# Pulls the powder case out of the hoist, and lifts it into the rammer tray.
# Verifies that the case is back against the rammer spade.
# Clears his arms from the tray.
The Projectile-Man:{{r|NavOrdAndGunV1|page=175}}
# Verifies that the powder case is in the rammer tray.
# Pulls the projectile out of the waist high projectile hoist.
# Places projectile in front of the powder case in the tray.
# Clears his arms from the tray.
# Pulls down on the '''RAMMER CONTROL''' (''see RAMMER CONTROL at the upper left corner of picture'').
Rammer Load Cycle:{{r|NavOrdAndGunV1|page=172}}
# Pulling down on the Rammer Control lever opens hydraulic valves inside the Rammer Controller.
# The opened valves port high pressure hydraulic fluid to the [[hydraulic cylinder|"Hydraulic Ram Cylinder"]] in the Slide behind the tray. The Ram Cylinder is connected to the "Rammer Cross Head". (The white horizontal bar behind the Spade in the picture.) The Cross Head supports the Rammer Spade as it moves in the tray. When the cylinder is pressurized, the Cross Head and Spade are driven forward in the Tray.
# As the spade moves forward, it pushes the projectile and powder case into the chamber. The spade's time of travel, from the rear of the tray to the breech, is one second. As it approaches the breech, the Cross Head pushes through a spring latch that locks it there.{{r|NavOrdAndGunV1|page=173}} At the same time, the Cross Head trips another lever connected to the Rammer Controller, and the Controller releases the hydraulic pressure to the Ram Cylinder.{{r|NavOrdAndGunV1|page=174}}
# When the powder case clears the top of the breech block, the block automatically rises.{{r|NavOrdAndGunV1|page=175}}
# The rising breech block displaces the rammer spade behind the powder case by pushing the spring-loaded spade up. This continues until the rammer spade is off the powder case, and the block has sealed the chamber.{{r|NavOrdAndGunV1|page=175}}
# The gun is loaded and ready to fire.
===Firing===
This gun can be fired either electrically or by percussion.<ref name="NavOrdAndGunV1"/>
When the gun fires, the following automatic events happen in two seconds:<ref name="GM3"/>
# During Recoil:
## The Rammer Crosshead is unlocked.
## The Rammer Control is pushed to the up position by a cam on top of the rearward moving Housing.
## With the Rammer Control up, the Rammer Controller ports high pressure hydraulic fluid to the retract side of the Rammer Cylinder, and the Rammer Crosshead and Spade drive back to the rear of the Rammer Tray.
# During Counter-recoil:
## The Firing Pin is cocked.
## The Breech Block is lowered.
## The spent Powder Case is ejected out of the Chamber, and back down the Rammer Tray. There it is caught by the gloved Hot Case Man, and thrown out of the mount.
## Just before the housing finishes returning to "In Battery", a valve is opened for a second, and a blast of compressed air is sent down the bore to clean it out.
The gun is ready to be reloaded.
==Gun mounts==
===Types===
[[File:5in-38 Open Mount.jpg|thumb|A Mk 21 5"/38 caliber open pedestal mount in 1942.]] [[File:USS Porter (DD-356) at Mare Island Navy Yard in July 1942.jpg|thumb|right|Two Mk 22 5"/38 caliber mounts aboard the destroyer {{USS|Porter|DD-356|6}}, 1942.]] [[File:5-inch 38-caliber cropped.jpg|thumb|right|[[United States Marine Corps|USMC]] crewed Mk 28 Mod 2 5"/38 caliber mount aboard {{USS|New Jersey|BB-62|6}}, 1984.]] [[File:Mark 37 5in-38cal mount.jpg|right|thumb|Left rear view of a Mark 37 5"/38 caliber mount. NOTE: No Fuze Setter.]] [[File:Bow of USS Hamner (DD-718), in 1971.png|thumb|right|Forward Mk 38 5"/38 caliber mount aboard the destroyer {{USS|Hamner|DD-718|6}}.]][[File:WW2 Naval 5-inch gun preserved at Zuoying,Kaohsiung.jpg|thumb|right|The World War II Naval 5"/38 gun preserved in the ROC Marine Corps History Museum in Zuoying, Kaohsiung, Taiwan.]] There are four basic [[weapon mount|mount]] types:
;Twin {{r|NavOrdAndGunV1|page=158}}:
* All sat on a base ring stand, and had an ammunition handling room, called the Upper Handling Room (as it was above the main magazine), below the mount.
* They all had:
** Horizontal periscopic sights with movable-[[prism sight]] setting.
** Two powered, fuze setting, projectile hoists.
** Two powered powder case hoists.
** Powered training and elevating drives (in this context, "training" means rotating the mount on its stand).{{r|NavOrdAndGunV1|page=47}}
* This mount was the standard installation on battleships, cruisers, early [[destroyer leader]] ({{sclass|Porter|destroyer|5}}, {{sclass|Somers|destroyer|5}}) classes (these mounts on the DL's were single-purpose/anti-surface ship only),<ref name="5/38"/> and later destroyers (starting with the {{sclass|Allen M. Sumner|destroyer|4}}). It was also used on the island (starboard) side of the {{sclass|Essex|aircraft carrier|1}}s.{{r|NavOrdAndGunV1|page=47}}
;Enclosed single:
:All enclosed single mounts sat on a base ring stand, and had an upper handling room. The enclosed single mount was used on some early destroyer classes ({{sclass|Gridley|destroyer|5}} (1937) up to and including the {{sclass|Fletcher|destroyer|4}} (1942)), but by the end of World War II, it was mainly found on the many minelayers and auxiliaries which were developed from the older classes of destroyers, as well as on most of the [[Destroyer Escort|destroyer escorts]], and many large auxiliaries (repair ships, destroyer tenders, etc.).<ref name="NavOrdAndGunV1"/>
;Open single base ring mount:
:Open mount with Upper-Handling Room. Used on the port and starboard gangways, just below the flight deck, on {{sclass|Yorktown|aircraft carrier|1}}s<ref name="NavOrdAndGunV1"/> and {{sclass|Benham|destroyer|5}} through {{sclass|Gleaves|destroyer|0}} destroyers.
;Open single pedestal mount:
:This was the first 5"/38cal type installed. It was put on the {{sclass|Farragut|destroyer|1||1934}}s in 1934 through to the {{sclass|Bagley|destroyer|4}} (1937). Some of these mounts placed on ship's forecastles were partially enclosed to protect the crew against bow spray, but they were still considered an open mount. Since these mounts did not have Upper Handling Rooms, they could be installed on ships without extensive reconstruction. For that reason, they were frequently used on [[Defensively equipped merchant ships|armed merchant ships]].<ref name="NavOrdAndGunV1"/>
''Farragut'' and ''Mahan'' had only open mounts. The ''Gridley'' class introduced the enclosed single gun house, but not all of its guns were enclosed. The ''Benham'' class replaced all pedestal mounts with open base ring mounts later on. The ''Fletcher'' class was the first to only have enclosed guns (except for the ''Porter'' and ''Somers'' destroyer leaders).
There are several models of the 5"/38, differentiated by the word ''Mark'' (or its abbreviation ''MK'') and a number. Variations to the basic design are called ''Modifications'' (or its abbreviation ''Mod''). For instance, '''5"/38 MK&nbsp;21''' is a single-barrel open pedestal mount widely used on amphibious ships, auxiliaries, and merchant ships. The '''5"/38 MK&nbsp;30''' is a single enclosed base ring mount widely used on [[destroyer escort]]s. The '''5"/38 MK&nbsp;38''' is a twin mount specifically designed for newer destroyers.
{| class="wikitable" align="center"
|+ '''5"/38-caliber gun mounts'''<ref name="5/38"/>
|-
! Mark/mod
! Barrels
! Weight
! Design
! Use
|-
|align="center"|Mk21||align="center" |Single||align="center"| {{convert|31200|lb|kg|abbr=on}}||align="center"|Open pedestal||Some 1930s built combatants, auxiliaries, merchant ships
* destroyers
** 8 {{sclass|Farragut|destroyer|0||1934}}(1932) (5x1)
** 16 {{sclass|Mahan|destroyer|0}}(1934) (5x1)
|-
|align="center"|Mk22||align="center" |Twin||align="center"|{{convert|75250|lb|kg|abbr=on}}||align="center"|Enclosed base ring||
* destroyer leaders
** 8 {{sclass|Porter|destroyer|0}}(1933) (4x2)
** 5 {{sclass|Somers|destroyer|0}}(1935) (4x2)
|-
|align="center"|Mk24||align="center" |Single||align="center"|{{convert|29260|lb|kg|abbr=on}}||align="center"|Open pedestal||1930s built aircraft carriers
* destroyers
** 4 {{sclass|Gridley|destroyer|0}}(1935) (aft 2x1)
** 8 {{sclass|Bagley|destroyer|0}}(1935) (aft 2x1)
** 2 {{sclass|Mahan|destroyer|0}}(1936) (aft 3x1)
* cruisers
** {{USS|Wichita|CA-45|2}} (4/8)
|-
|align="center" |Mk28 Mod0 ||align="center" |Twin||align="center"|{{convert|156295|lb|kg|abbr=on}}||align="center"|Enclosed base ring||Pre-''Iowa''-class battleships
|-
|align="center" |Mk28 Mod2 ||align="center" |Twin||align="center"|{{convert|170635|lb|kg|abbr=on}}||align="center"|Enclosed base ring||''Iowa''-class battleships
|-
|align="center" |Mk29 Mod0 ||align="center" |Twin||align="center"|{{convert|108000|lb|kg|abbr=on}}||align="center"|Enclosed base ring||Cruisers, [[USS Atlanta (CL-51)|''Atlanta''-class light cruisers]]
|-
|align="center" |Mk30 Mod0||align="center" |Single||align="center"|{{convert|40900|lb|kg|abbr=on}}||align="center" |Enclosed base ring||Destroyers, auxiliaries, USCG high endurance cutters
* cruisers
** {{USS|Wichita|CA-45|2}} (4/8)
|-
|align="center" |Mk30 Mod1||align="center" |Single||align="center"|{{convert|33500|lb|kg|abbr=on}}||align="center"|Open base ring||Destroyer rear mounts, escort carriers
* 10 {{sclass|Benham|destroyer|0}}(1935) (aft 2x1)
* 12 {{sclass|Sims|destroyer|0}}(1937) (aft 2x1 out of 3x1)
* 30 {{sclass|Benson|destroyer|0}}(1938) (aft 2x1 out of 3x1)
* 66 {{sclass|Gleaves|destroyer|0}}(1938) (aft 2x1 out of 3x1)
|-
|align="center" |Mk30 Mod69||align="center" |Single||align="center"|{{convert|45000|lb|kg|abbr=on}}||align="center"|Enclosed base ring||Destroyer escorts with the upper rear edge of the Mark 38 blast shield beveled to clear [[hedgehog (weapon)|hedgehog]] projectiles from a launcher astern of the gun mount<ref>Franklin, Bruce Hampton (1999) ''The Buckley-class Destroyer Escorts'' Naval Institute Press {{ISBN|1-55750-280-3}} p. 34</ref>
|-
|align="center" |Mk32 Mod0||align="center" |Twin||align="center"|{{convert|105600|lb|kg|abbr=on}}||align="center"|Enclosed base ring||Cruisers, aircraft carriers
|-
|align="center" |Mk32 Mod4||align="center" |Twin||align="center"|{{convert|120369|lb|kg|abbr=on}}||align="center"|Enclosed base ring||Cruisers, aircraft carriers
|-
|align="center" |Mk37 Mod0||align="center" |Single||align="center"|{{convert|34700|lb|kg|abbr=on}}||align="center"|Open pedestal||Armed merchants, auxiliaries
|-
|align="center" |Mk38 Mod0||align="center" |Twin||align="center"|{{convert|95700|lb|kg|abbr=on}}||align="center" |Enclosed base ring||Destroyers
|}
===Ammunition delivery===
Since this gun fires semi-fixed ammunition, each round is delivered to the gun in two pieces{{em dash}}a projectile and a powder case.<ref name="NavOrdAndGunV1"/>
;Base ring mounts
:The ready service ammunition is kept in the upper handling room just below the mount. The projectile travels up to the gun room (also called the gun house) through an electric-hydraulic hoist.<ref name="NavOrdAndGunV1"/> It arrives next to the projectile-man nose down and waist high. If the projectile has a time fuze, the fuze is automatically set as it goes up the hoist, and the hoist maintains the ordered fuze setting from the fire control system as long as the projectile stays in the hoist.<ref name="NavOrdAndGunV1"/> The powder case is sent up through a powder scuttle in the gun room's deck just next to the powder man's feet.<ref name="NavOrdAndGunV1"/> It arrives with its base up, and the primer covered with a protector called the "Butterfly". The men in the upper handling room hand carry the projectiles and powder cases from the ready service racks to the lower ends of the hoists while avoiding the equipment hanging down from the rotating mount. In a twin mount executing "Rapid continuous fire" (the firing keys are held closed, and the gun fires as soon as the breech closes), the crew move 30 to 44 projectiles and powder cases per minute.
;Pedestal mounts
:The ready service ammunition is kept in lockers or compartments arrayed around the mount. The projectiles and powder cases are hand carried from ready service to the left side of the moving mount. The projectile is placed nose down in one of three Fuze Setter Mechanisms (commonly called fuze pots) on the mount. If the man is delivering a projectile with a mechanical time fuze, he then spins a hand crank just in front of that fuze setter mechanism. This would dial in the ordered fuze time into that projectile. The powder case is placed in a rack bolted to the mount's deck just behind the powder-man's feet.
===Mount crew===
Depending on the mount, a 5"/38-caliber gun could have a crew of 15 to 27 personnel in the gun room and upper handling room.<ref>{{Cite book |title=Naval Ordnance And Gunnery, Volume 1, Naval Ordnance, NAVPERS 10797-A |publisher=US Navy, Bureau of Naval Personnel |year=1957 |edition=1957 |location=Washington, DC |quote=Approximately 27 men are required to man all stations in the mount and the upper handling room.}}</ref> This does not include the personnel needed in the magazines during extended actions. There were two modes of mount operation that the crew was trained and expected to know. The primary mode was "automatic control", where the mount was slaved to the fire control system. But if the fire control system was damaged, or if the ship's power was out, the mount could continue the action in "local control". In US service, most gun crews were US Navy personnel. Even the civilian [[United States Merchant Marine|Merchant Marine]] ships had a small detachment of the [[United States Navy Armed Guard|Navy Armed Guard]] on board to operate the 5"/38 and other guns. One exception to this was on ships with a [[USMC|Marine Detachment]], where the Marines manned one of the mounts, usually decorated with the [[Eagle, Globe, and Anchor|Marine emblem]] (''see the USMC emblem on USS New Jersey's Mk&nbsp;28, Mod&nbsp;2 mount picture above'').
;Mount captain
:A senior Petty Officer or Gunnery Sergeant who was in command of the mount. In enclosed mounts, he stood on an interior platform that was located half way up the back bulkhead of the enclosure. There was a hatch on the top of the enclosure where he could stick his head and shoulders out the mount's top. On some mounts, this hatch had a steel hood welded around the back and sides (''see an example of this hood in the USS New Jersey picture''). This hood protected the Mount Captain from the muzzle blasts of adjacent weapons. He was wearing a [[Sound-powered telephone|sound powered telephone]] so that he could receive action orders from the battery commander, and send mount status reports back. Covering the telephone headset, there was a helmet specially designed to fit over the phone. Around his neck, he had a pair of gunnery binoculars which had a reticle scaled in [[angular mil]]s. By ducking his head down into the mount, he could see the entire interior of the mount from his platform. Next to him was a voice tube down to the upper handling room. At arms length, he had switches for controlling communication, emergency lighting, and battle lanterns.<ref name="NavWeaps5in38crew">{{Cite web |url=http://www.navweaps.com/Weapons/WNUS_5-38_mk12_Crews.php |title=How the 5"/38 crews operated |access-date=2 March 2018}}</ref> His duties during Automatic Control were to receive action orders from the battery commander (e.g., "Mount&nbsp;51, plot. Surface action starboard. Target destroyer. Bearing&nbsp;060. Range nine thousand, five hundred yards. Slow salvo."), give the appropriate orders to his Gun Room and Upper Handling Room crews (e.g., "Match pointers. Switch to automatic. Handling room fill the hoists with able able common and full service charge. Standby for slow salvo."), verify that his orders were being followed, and report his gun's status back to the battery commander (e.g., "Plot, mount&nbsp;51 in auto. Bore clear."). In Local Control, he aimed and fired his mount's gun(s){{em dash}}sometimes without external help. With his gunnery binoculars, he estimated the range to the target, and its bearing rate. He then mentally converted these into range and deflection orders to his Sight Setter. After firing, he observed the fall of his shot, and made sight corrections to his Sight Setter if necessary.
;Gun Captain
:The Gunner's Mate(s) responsible for maintaining the mount. Daily, he went through a process of checking fluid levels, lubricating bearings, cleaning gun sights, cycling powered equipment, testing firing systems, checking gas pressures, and verifying that all the equipment that would be needed in an action was in his mount. In twin mounts, there would be a gun captain assigned to each gun assembly. The gun captain usually stood on his foot-high tool box that was welded to the mount's deck, and offset from the gun's centerline (''see the man in black standing on the box in the MK21 open mount picture''). This placed him high and aft of the rammer motor. From there, he could watch the actions of the powder-man, projectile-man, breech block, and rammer. He could verify that the gun returned to battery before the next round was loaded. If something went wrong, he was free to move around his gun to fix the problem. He knew everyone's job, and could step in if necessary. At the mount captain's command, he manually opened the breech block before the first round was loaded, and reported if the bore is clear.<ref name="NavWeaps5in38crew"/> His duties were the same in automatic or local control.
;Pointer
:[[File:5in38calElvIndReg.jpg|right|thumb|Single Mount Elevation Indicator Regulator]] Controlled the mount's elevation and firing. He sat in the left front corner of the mount. In front of him were his optical sight, hand wheels, and elevation drive controls. To his right, about elbow high, was a large box called the '''Elevation Indicator Regulator''' (''pictured''). This box controlled the elevation power drive. Through a window on top of the box, he could see a set of dials that indicated the elevation of the gun, and the automatic elevation orders coming from the Fire Control System. Above the Indicator Regulator was the '''Electrical Fire Select Switch'''. It was a rotary switch with three positions: Off, Local, and Auto. Off disabled the electrical firing system on the mount. Local enabled the electric firing key on his right hand wheel. Auto enabled the off-mount electrical firing circuit from the Fire Control System. Just outside his right knee was the '''Percussion Select Lever'''. This mechanical lever had two positions: Safe, and Armed. When it was in the armed position, the mechanical linkage for percussion firing was enabled. His right footrest was at one end of this linkage, and the firing pin [[Sear (firearm)|sear]] in the breech block was at the other. By rocking his right foot forward, he fired the gun. Electrical firing was the primary firing method. When the Mount Captain commanded "Match pointers. Switch to Automatic," he looked down at the dials on his Indicator-Regulator. The dials told him the difference between the gun's present elevation and the ordered elevation electrically coming from the Fire Control System by [[synchro]]. He changed the elevation of the gun, by moving his hand wheels, until the dial difference was zero. His dials were now "matched", and he switched the elevation drive into Auto. This disengaged his hand wheels, and gave elevation control to the Fire Control System. Then he moved the Electrical Fire Select Switch to "AUTO", and reported back to the Mount Captain, "Elevation in auto." He would now look through his sight, and if the Sight Setter had matched the sight-setter dial pointers, he would see the target in the cross-hairs. When the Mount Captain commanded "Switch to Local", he switched the elevation drive and the Electrical Fire Select Switch to local. In local control, he controlled the gun's elevation with his hand wheels to keep his sight's horizontal cross hair on the target. At the command of the Mount Captain, he fired the gun by squeezing the firing key on his right hand wheel.
;Trainer
:[[File:5in38calTrnIndReg.jpg|right|thumb|Single Mount Train Indicator Regulator]]Controls the mount's train angle (bearing). He sits in the right front corner of the mount (''see the far right man in the Mk21 open mount picture''). In front of him, are his optical sight, hand wheels, and train drive controls. Between his knees is a large box called the '''Train Indicator Regulator'''. (''pictured'') This box controls the train power drive. On top of the box, is a window with a set of dials that indicate the train angle of the gun, and the automatic train orders electrically coming from the Fire Control System by [[synchro]]. When the Mount Captain commands, "Match pointers. Switch to Automatic.", he looks down at the dials on his Indicator-Regulator. The dials also tell him the difference between the gun's present train angle and the ordered train angle. He changes the bearing of the gun, by moving his hand wheels, until the dial difference is zero. His dials are now "matched", and he switches the train drive into Auto. This disengages his hand wheels, and gives train angle control to the Fire Control System. Then, he reports back to the Mount Captain, "Train in auto." He may now look through his sight, and if the Sight Setter has matched the sight-setter dial pointers, he will see the target in the cross-hairs. When the Mount Captain commands, "Switch to Local", he switches the train drive to local. In local control, he controls the gun's train angle with his hand wheels to keep his sight's vertical cross hair on the target.
;Sight setter
:[[File:5in38calSghtSttrDials.jpg|right|thumb|Single Mount Sight Setter Dials]] Operates the sight setting equipment. In single mounts, he stands just behind the trainer (''see the man with headphones in the Mk21 open mount picture''), while in twin mounts he sits between the guns, just forward of the projectile hoists. The sight setter moves the sights' reticles relative to the barrel's axis. In early open mounts, this was done by moving the platforms to which the sights were bolted. Sights in enclosed mounts have movable prisms in their optical paths.<ref>{{Cite book |title=Naval Ordnance and Gunnery, Volume 1, Naval Ordnance, NAVPERS 10797-A |publisher=US Navy, Bureau of Naval Personnel |year=1957 |location=Washington, DC |quote=Movable prism-type telescopes are mounted at the pointer’s, checker’s, and trainer’s stations.}}</ref> The sight setter has three dials, and two hand cranks. (''pictured'') The two right dials and right hand crank control the elevation reticle offset (called Sight Angle<ref>{{Cite book |title=Gunner's Mate 3, Vol. 1, NAVPERS 10158-A |publisher=US GPO |date=1952 |location=Washington, DC |page=32}}</ref>). The upper right dial is scaled in [[Minute of arc|minutes of arc]], and the lower right dial is in yards. The left dial and hand crank control the reticle's left and right offset (called Sight Deflection<ref>{{Cite book |title=Gunner's Mate 3, Vol. 1, NAVPERS 10158-A |publisher=US GPO |date=1952 |location=Washington, DC |page=38}}</ref>), and the dial is scaled in [[angular mil]]s. When the mount is in Automatic Control, he turns his hand cranks to keep index marks on his dials matched to lines on the central disks of the dials. These disks are electrically controlled by the Fire Control System by [[synchro]].<ref name="GM3p66">{{Cite book |title=Gunner's Mate 3, Vol. 1, NAVPERS 10158-A |publisher=US GPO |date=1952 |location=Washington, DC |page=66}}</ref> This is called matching the pointers,<ref name="GM3p66"/> and it allows the sights to remain on the target while the mount is controlled by the Fire Control System. In local control, he takes sighting orders from the Mount Captain in yards of range and mils of deflection.
;Fuze setter
:[[File:5in38calFzIndReg.jpg|right|thumb|Single Mount Fuze-setting Indicator Regulator]]He operates the equipment which sets the fuze time on projectiles with mechanical time fuzes. On a single enclosed mount, he sits below and just outboard of the Pointer's seat. Under the Pointer's seat, and in front the Fuse Setter, is the '''Fuse Indicator Regulator'''. (''pictured'') It is a box with a window, a hand crank, and a selector lever. On a twin mount, he and his Fuze Indicator Regulator sit next to the Sight Setter between the guns. When the mount is put in Automatic control, he flips the selector lever to Auto, and this electrically powered Fuze Indicator Regulator automatically follows the fuze setting orders sent from the Fire Control System by [[synchro]]. In Local Control, he follows the Mount Captain's fuze orders by spinning the hand crank until the dials in the window read the correct fuze time.
;Powder-man
:Slides the primer protector off the powder case, and then lifts the case from the powder scuttle at his feet to the gun's rammer tray.
;Projectile-man
:Moves the projectile from the hoist to the rammer tray in front of the just-placed powder case, and then he pulls the rammer lever to load the projectile and powder case into the chamber.
;Hot case man
:When the gun fires, he catches the ejected powder case and throws it out of the mount.
;Check sight
:He verifies that the mount is aiming at the target.
==Ammunition==
[[Image:Semi-fixed round in chamber.jpg|right|thumb|Drawing of loaded Semi-Fixed round.]]
This gun uses semi-fixed ammunition. (''Pictured'')<ref name="NavOrdAndGunV1"/> (Also called Separated Ammunition.)<ref name="NavWeapsDefsPt2">{{cite web |url=http://www.navweaps.com/Weapons/Gun_Data_p2.php |title=Definitions and Information about Naval Guns: Part 2 – Ammunition, Fuzes, Projectiles and Propellants |access-date=2 March 2018}}</ref> Each round consists of a projectile and a powder case. The two parts of the round are kept separate until they get to the gun.<ref name="GM3"/> At the gun, they are first combined on the rammer tray, and then power rammed into the chamber together with one ram cycle. The powder case completely fills the volume of the chamber, and its length seats the projectile's rotating band into the bore's rifling. This is different from a naval bag gun. In a bag gun: (1) The projectile, by itself, is power rammed into the chamber until its rotating band is seated in the bore's rifling. (2) The rammer is retracted. (3) The powder bags are then rammed in.<ref name="GM3"/> This is also different from some artillery field guns: (1) The projectile is hand rammed into the chamber with a ramrod until its rotating band is seated in the bore's rifling. (2) The ramrod is retracted. (3) Next powder is placed in the chamber either as a bag or primed canister with the required charge. Note that the single ram operation used in semi-fixed guns decreases the loading time, and therefore increases the firing rate on medium and large caliber guns. For example, each of the nine 8"(203&nbsp;mm)/55-caliber Rapid-Fire guns installed on the {{sclass|Des Moines|cruiser|1}} used auto-loaded semi-fixed ammunition and had a firing rate of 10 to 12 rounds a minute.<ref name="5/38"/> See also the [[8"/55 caliber Mark 71 gun]]. 5” rounds were often used as weights for burials at sea.
===Projectile===
[[Image:5in 38cal AntiAircraft Common.jpg|right|thumb|5"/38cal Anti-Aircraft Common (AAC) projectile.]]
The Projectile (''pictured'') has three major parts: the body, the fuze, and the explosive charge.<ref name="NavOrdAndGunV1"/>
;Projectile body
The body is basically a machined steel tube with an [[ogive]] shape at one end. At the ogive and rear ends are threaded openings used to the install the shell's filler and hold the fuzes. Around the tube near the base is a copper alloy ring called the '''Rotating Band'''. This band has a diameter larger than the bore, and when the projectile and powder case are rammed into the chamber, the band is jammed into the grooves of the bore's rifling. It forms a gas seal between the projectile and the bore. Also, as the projectile travels down the barrel, the band grips the rifling to impart spin to the projectile.<ref>{{Cite book |title=Naval Ordnance And Gunnery, Volume 1, Naval Ordnance, NAVPERS 10797-A |publisher=US Navy, Bureau of Naval Personnel |year =1957 |edition=1957 |location=Washington, DC |page=29 |quote=The three primary functions of the rotating band are to seal the bore, to position and center the rear end of the projectile, and to impart rotation to the projectile.}}</ref>
;Fuze
The [[fuze|Fuse]] detonates the projectile to cause maximum damage to the target. Different targets required different fuzes. The safety requirements of a fuze are that... {{r|NavOrdAndGunV1|page=33}}
* ... it is safe to handle. (i.e.: It will not arm if dropped, rolled, or shaken.) {{r|NavOrdAndGunV1|page=33}}
* ... it remains unarmed in the bore, and until the projectile is well clear of the firing ship to protect exposed personnel. {{r|NavOrdAndGunV1|page=33}} Therefore, when the gun is fired, the following events take place:
** 14,000g acceleration {{r|NavOrdAndGunV1|page=34}} from the burning propellant in the bore. This acceleration is used to setback (i.e.: Force to the rear.) {{r|NavOrdAndGunV1|page=34}} some fuze parts from unarmed to armed positions due to their [[inertia]].
** [[Centrifugal force]] from the 12,360 rpm {{r|NavOrdAndGunV1|page=34}} projectile rotation. This force causes other parts to move outward.{{r|NavOrdAndGunV1|page=34}}
** 7.2g deceleration {{r|NavOrdAndGunV1|page=34}} from [[aerodynamic drag]] after the projectile leaves the muzzle. Due to [[inertia]], other movable parts will creep {{r|NavOrdAndGunV1|page=34}} forward.
All of these events must take place in the correct order to arm the fuze.
List of fuze types:<ref name="NavOrdAndGunV1"/>
;Mechanical time fuze
:A nose time fuze that detonates the shell after an adjustable time interval has elapsed since firing.<ref>{{Cite book |title=Naval Ordnance And Gunnery, Volume 1, Naval Ordnance, NAVPERS 10797-A |publisher=U.S. Navy, Bureau of Naval Personnel |year=1957 |edition=1957 |location=Washington, DC |quote=... time fuzes are clockwork mechanisms used to obtain timed air bursts.}}</ref>
;Base detonating fuze
:A base impact fuze screwed into the rear of a projectile to protect the fuze during impact. It delays the shell's detonation about 25&nbsp;[[Millisecond|ms]] after impact, allowing the projectile to penetrate the target prior to detonation.<ref name="NavOrdAndGunV1"/>
;Point detonating fuze
:A nose impact fuze. Very fast detonation on the surface of the target.
;VT fuze
:The VT (Variable Time, this is a counter-espionage decoy designation) fuze is a [[proximity fuze]].<ref>{{Cite book |title=Naval Ordnance And Gunnery, Volume 1, Naval Ordnance, NAVPERS 10797-A |publisher=US Navy, Bureau of Naval Personnel |year=1957 |edition=1957 |location=Washington, DC |quote=The radio proximity or VT fuze is used in all of the types of projectiles which can use mechanical time fuzes...}}</ref> It is a nose electronic fuze that does not require impact to trigger.<ref>{{Cite book |title=Naval Ordnance And Gunnery, Volume 1, Naval Ordnance, NAVPERS 10797-A |publisher=US Navy, Bureau of Naval Personnel |year=1957 |edition=1957 |location=Washington, DC |quote=Point detonating, time, and VT fuzes may all be called nose fuzes ...}}</ref>  Designed to detonate close to the target. It was originally intended to be used against air targets. Now it is also used in shore bombardment and surface actions against fast boats. This is because the VT fuze has proved well suited for bursting the shell at the correct distance above the ground or water for maximum damage to lightly armored targets over a large area.<ref>{{Cite book |title=Naval Ordnance And Gunnery, Volume 1, Naval Ordnance, NAVPERS 10797-A |publisher=US Navy, Bureau of Naval Personnel |year=1957 |edition=1957 |location=Washington, DC |quote=VT-fuzed ammunition is very effective on exposed personnel and lightly armored targets ...}}</ref>
;Auxiliary detonating fuze
:In the projectile drawing, an Auxiliary Detonating Fuze is screwed onto the bottom of the Mechanical Time Fuze. This is because the time fuze primer does not have enough explosive shock to detonate the relatively insensitive Explosive "D". The Auxiliary fuze uses an intermediate explosive that is set off by the time fuze primer, and in turn, sets off the Explosive "D".<ref name="NavOrdAndGunV1"/>
{| class="wikitable"
|+5"/38 cal projectiles<ref name="NavOrdAndGunV1"/><ref name="5/38"/>
|-
! Body label
! Full name
! Description
|-
| AA
| Anti-aircraft
| A high capacity fragmenting shell with a nose mechanical time fuze
|-
| AAC
| Anti-aircraft common
| A medium penetrating shell with a mechanical time fuze and a base detonating fuze. Designed to be used on either aircraft or lightly armored ships. For aircraft, the time fuze is set to explode the shell just before it reaches the target. The detonation shock wave and the expanding cone of shrapnel increases the chance of target destruction. For vessels, the time fuze is left on safe, and the base detonating fuze will explode the shell 25&nbsp;milliseconds after impact.
|-
| AAVT
| Anti-aircraft VT
| A high capacity fragmenting shell with a VT (proximity) fuze.
|-
| AP
| Armor-piercing
| A thick walled penetrating projectile with a base detonating fuze. The explosive charge is usually [[Explosive D]] because it is less sensitive to impact.<ref name="NavOrdAndGunV1"/>
|-
| SS
| [[Star shell]]
| A thin walled shell with a mechanical time fuze. Packed inside is a flare attached to a parachute. When the fuze fires, a small black powder charge expels the flare and parachute out the back. Before radar, star shells were used to illuminate the target at night. They are still used in support of troops at night, or illumination of an at sea rescue.
|-
|WP
|[[White phosphorus]]
|A thin walled shell with a point detonating fuze used for smoke screens. It also has some incendiary effect.
|-
|AA non-frag
|Anti-Aircraft non-fragmentation
|A thin walled shell with a mechanical time fuze and packed with a smoke producing chemical that is ejected out the rear by a small black powder charge. It is used in practice anti-aircraft shoots.
|-
|AAVT non-frag
|Anti-Aircraft VT non-fragmentation
|A thin walled shell with a VT fuze and packed with a smoke producing chemical that is ejected out the rear by a small black powder charge. It is used in practice anti-aircraft shoots.
|-
|BL
|Blind load
|A shell without a fuze, and filled with sand. It is used in practice surface shoots.
|-
|W
|[[Chaff (radar countermeasure)|Window]]
|A thin walled shell with a mechanical time fuze and packed with strips of metal foil that is ejected out the rear by a small black powder charge. It is used to confuse enemy radar.
|}
===Powder case===
[[Image:5in 38cal Full Service Charge.jpg|right|thumb|5"/38cal Full Service Charge.]]The '''powder case''' is a brass or steel alloy cylinder closed at one end. It holds the propelling charge and a case combination primer. The charge is held packed around the primer by a wad, distance piece (not in clearing charge), and plug.<ref>{{Cite book |title=Naval Ordnance And Gunnery, Volume 1, Naval Ordnance, NAVPERS 10797-A |publisher=US Navy, Bureau of Naval Personnel |year=1957 |edition=1957 |location=Washington, DC |quote=In 40 mm and larger guns, a cardboard disc, or wad, is forced into the case and a distance piece, if one is needed, placed on top.}}</ref> When rammed in the chamber with the projectile, the Full and Reduced charge cases are designed to completely fill the volume of the chamber from the breechblock face to the base of the projectile when its rotating band is jammed into the bore's rifling.<ref name="NavOrdAndGunV1"/> In other words, the powder case acts a rammer extension for the projectile. There are three types of powder cases:
:'''Full service charge''' (''pictured'')
::A 26.7 inch (679 mm) long, 12.3 pound (5.6&nbsp;kg) brass case with 15.5&nbsp;pounds (7.0&nbsp;kg) of [[smokeless powder|smokeless or flashless (used at night) powder]].<ref name="5/38"/> The Full Service Charge new gun initial velocity is {{convert|2,600|ft/s|m/s|abbr=on}}.<ref name="5/38"/> It is used in surface and anti-aircraft actions.<ref name="NavOrdAndGunV1"/>
:'''Reduced charge'''
::The Reduced Charge uses the same case as the Full Service Charge, but with only {{convert|3.6|lb}} of powder and a longer distance piece.<ref name="5/38"/> The Reduced Charge new gun initial velocity is {{convert|1,200|ft/s|m/s|abbr=on}}.<ref name="5/38"/> It is used in shore bombardment to lob shells, like a [[mortar (weapon)|mortar]], over obstacles to hit targets on the opposite side, and for propelling star shells at a lower velocity to protect the parachute from being shredded while it is deployed.<ref name="NavOrdAndGunV1"/>
:'''Clearing charge''' (''Pictured'')
[[Image:5in 38cal Clearing Charge.jpg|right|thumb|5"/38cal Clearing Charge.]]
::The clearing charge (also called, "the short round") is a short case; plugged just above the wad.<ref name="NavWeapsDefsPt2"/> The distance piece between the wad and plug is left out. Its powder charge is less than a full service charge.<ref name="NavWeapsDefsPt2"/> This case is essential for the safety of the mount because it is needed to clear a gun after a misfire.<ref name="NavWeapsDefsPt2"/> Due to its importance, it is kept in a special container in the mount whenever the ship is in a combat zone. A misfire is especially dangerous in semi-fixed guns.<ref name="GM3"/> When the breech is opened after the misfire, the faulty powder case can be extracted, but the projectile will remain jammed in the rifling.<ref name="NavWeapsDefsPt2"/> Also, all or part of the extracted case's cork plug may still be wedged in the chamber behind the projectile. This "fouls" the chamber because it decreases the chamber's volume. And, since Full and Reduced charge cases take up the full volume of an unfouled chamber (see loaded Semi-Fixed round drawing above), any residue left from the previously extracted case will prevent them from fully loading into the chamber. Therefore, the clearing charge is made short so that it will fit into a fouled chamber.
::After hand extracting the bad case from the chamber, the clearing charge is removed from its special container and is hand rammed into the chamber. With the clearing charge sealed in the chamber, the projectile is fired out the muzzle.<ref name="GM3"/> It is important to clear the projectile through the muzzle because it is not easy nor safe pushing a bore rod down the barrel to force a fuzed projectile back through the chamber and into the gun house.<ref>{{Cite book |title=Naval Ordnance And Gunnery, Volume 1, Naval Ordnance, NAVPERS 10797-A |publisher=US Navy, Bureau of Naval Personnel |year=1957 |edition=1957 |location=Washington, DC |quote=Whether a gun is hot or cold, the risks attendant upon removing a loaded and fuzed projectile seated in the bore, by backing out, are considered unwarranted...}}</ref> Also, if the gun has fired a number of rounds just prior to the misfire, time is critical because the barrel may be hot enough to [[cook off]] the high explosive in the projectile.<ref>{{Cite book |title=Naval Ordnance And Gunnery, Volume 1, Naval Ordnance, NAVPERS 10797-A |publisher=US Navy, Bureau of Naval Personnel |year=1957 |edition=1957 |location=Washington, DC |quote=A loaded and fuzed projectile, seated in the bore of a gun that is hot from previous firing, presents a hazard, since detonation of the projectile is possible as a result of being heated.}}</ref> This would destroy the mount.<ref name="GM3"/>
==Deployment==
(to be moved to a suitable page)
{{Hidden begin |showhide=left
| titlestyle=background:#ccccff
| title=Ships launched with 5-inch/38 guns
}}
Aircraft carriers
* 3 {{sclass|Yorktown|aircraft carrier|0}} 8
* {{USS|Wasp|CV-7|2}} 8
* 24 {{sclass|Essex|aircraft carrier|0}} 12
Escort Carriers
* 50 {{sclass|Casablanca|escort carrier|0}} 1
* 19 {{sclass|Commencement Bay|escort carrier|0}} 2
Battleships
* 2 {{sclass|North Carolina|battleship|0}} 20
* 3 of 4 {{sclass|South Dakota|battleship|0||1939}} 20
* {{USS|South Dakota|BB-57|2}} 16
* 4 {{sclass|Iowa|battleship|0}} 20
Heavy cruisers
* {{USS|Alaska|CB-1|2}} 12
* {{USS|Guam|CB-2|2}} 12
* {{USS|Wichita|CA-45|2}} 8
* 14 {{sclass|Baltimore|cruiser|0}} 12
* 3 {{sclass|Oregon City|cruiser|0}} 12
* 3 {{sclass|Des Moines|cruiser|0}} 12
Light cruisers
* 2 {{sclass|Brooklyn|cruiser|0}} 8
* 4 {{sclass|Atlanta|cruiser|0}} 16
* 4 ''Atlanta'' (''Oakland'') 12
* 27 {{sclass|Cleveland|cruiser|0}} 12
* 2 {{sclass|Fargo|cruiser|0}} 12
* 3 {{sclass|Juneau|cruiser|0}} 12
Destroyers
* 8 {{sclass|Farragut|destroyer|0||1934}} 5
* 8 {{sclass|Porter|destroyer|0}} 8
* 18 {{sclass|Mahan|destroyer|0}} 5
* 4 {{sclass|Gridley|destroyer|0}} 4
* 8 {{sclass|Bagley|destroyer|0}} 4
* 5 {{sclass|Somers|destroyer|0}} 8
* 10 {{sclass|Benham|destroyer|0}} 4
* 12 {{sclass|Sims|destroyer|0}} 5
* 6 {{sclass|Benson|destroyer|0}} 5
* 24 repeat-''Bensons'' 4
* 18 {{sclass|Gleaves|destroyer|0}} 5
* 48 repeat-''Gleaves'' 4
* 175 {{sclass|Fletcher|destroyer|0}} 5
* 58 {{sclass|Allen M. Sumner|destroyer|0}} 6
* 12 {{sclass|Robert H. Smith|destroyer|0}} 6
* 98 {{sclass|Gearing|destroyer|0}} 6
Destroyer escorts
* 22 {{sclass|Rudderow|destroyer escort|0}} 2
* 50 ''Rudderow''-APDs 1
* 83 {{sclass|John C. Butler|destroyer escort|0}} 2
* 6 {{sclass|Buckley|destroyer escort|0}} (launched as APDs) 1
Attack Transports
* 7 of 328 [[Type C2 ship]]
** 3 {{sclass|Ormsby|attack transport|0}} 2
** 4 {{sclass|Sumter|attack transport|0}} 2
Attack Cargo
* 74 of 328 [[Type C2 ship]]
** {{USS|Alhena|AKA-9|3}} 1
** 11 {{sclass|Arcturus|attack cargo ship|0}} 1
** 32 {{sclass|Tolland|attack cargo ship|0}} 1
** 30 {{sclass|Andromeda|attack cargo ship|0}} 1
{{Hidden end}}
==See also==
* [[List of naval guns]]
* [[List of naval anti-aircraft guns]]
* [[Naval gunfire]]
===Weapons of comparable role, performance and era===
* [[QF 4.7 inch Mark XI gun]] : British equivalent dual-purpose gun.
* [[QF 4.5 inch Mk I – V naval gun]] : British equivalent dual-purpose gun.
* [[12.7 cm SK C/34 naval gun]] : German equivalent limited to low-angle fire.
* [[12.8 cm FlaK 40]] : Dedicated anti-aircraft, land-based German gun of equal calibre.
* [[130 mm/50 B13 Pattern 1936]] : Soviet equivalent [[Naval gun|naval]] and [[Coastal gun|coastal]] gun.
* [[Canon de 138 mm Modèle 1929]] : French equivalent [[naval gun]].
* [[120 mm Italian naval gun|120 mm naval gun]] : Italian equivalent [[naval gun]].
* [[12.7 cm/50 Type 3 naval gun]] : Japanese equivalent [[naval gun]] mounted on most destroyers and competitive against surface targets
* [[10 cm/65 Type 98 naval gun]]: Japanese naval gun mounted on {{sclass|Akizuki|destroyer|0}} destroyers, aircraft carrier {{ship|Japanese aircraft carrier|Taihō||2}} and light cruiser {{ship|Japanese cruiser|Ōyodo||2}}, competitive in the anti-aircraft role
===Weapons of comparable role in successive U.S. Navy service===
* [[5-inch/54-caliber_Mark_16_gun|5"/54 caliber Mark 16 gun]] : 1945
* [[5"/54 caliber Mark 42 gun]] : 1953
* [[5"/54 caliber Mark 45 gun]] : 1971
==Notes==
{{Reflist}}
==External links==
{{Commons category}}
* [http://www.navweaps.com/Weapons/WNUS_5-38_mk12.php Detailed description and history 5"/38 including ammunition and Mark data]
* [http://www.gyrodynehelicopters.com/5_inch_38_cal__gun.htm Illustrated descriptions of MK 30 & MK 38, list of ammunition for all Marks]
* [http://www.destroyers.org/ordnance-articles/5_inch_twin.htm Illustrated description of MK 38]
* [http://www.maritime.org/doc/destroyer/fiveinch/index.htm Illustrated Operating Instructions for MK XXI model]
* [http://www.destroyers.org/ordnance-articles/dest_gun_ammu.htm Photos of 5"/38 ammunition]
* [http://www.eugeneleeslover.com/ENGINEERING/Naval_Ordnance_V1.html Naval Ordnance and Gunnery, 1957 Volume 1 Naval Ordnance NavPers 10797-A]
{{WWIIUSNavalWeapons}}
{{DEFAULTSORT:5 38 Caliber Gun}}
[[Category:Naval anti-aircraft guns|5 inch]]
[[Category:World War II naval weapons]]
[[Category:Naval guns of the United States]]
[[Category:127 mm artillery]]
[[Category:Military equipment introduced in the 1930s]]