AMMUNITION AND GUNNERY
Despite the present-day emphasis on missiles, gunscontinue to be
important offensive weapons.
As a Seaman, you may be required to man gunstations or serve as
a member of a magazine crew, so itis necessary that you have a
general knowledge of theammunition and guns in service.
It is not our intent, nor is it necessary, to discuss allthe
different types of ammunition and guns used in theNavy today. This
chapter does, however, contain muchinformation on guns, ammunition,
and gunnery ingeneral; information that should be very helpful to
youin meeting your early shipboard assignments.
Excluding small arms, Naval guns are classifiedaccording to
size. Within this classification, they aregrouped as major,
intermediate, or minor calibers.Major caliber guns range from 8
inches up to 16 inches.Intermediate calibers are greater than 3
inches and lessthan 8 inches. Minor caliber guns are 3 inches
LEARNING OBJECTIVE: Defineammunition. Differentiate between the
types ofammunition used aboard naval ships. Defineand explain the
different types of projectilesand propelling charges used in the
Navy.Explain the use of the magazine and magazinesprinkler
In a general sense, ammunition includes anythingthat is intended
to be thrown at the enemy or put in hispath to deter, injure, or
kill personnel, or to destroy ordamage materials. The term
ammunition is used in amuch narrower and more technical sense in
this book.Ammunition includes any projectile or explosiveweapon, as
well as components or parts thereof, but notguns or weapon
launchers and their parts.
Service ammunition is ammunition lit for serviceuse and
including all explosive and propellantcomponents. Inert ammunition
(that is, lackingexplosive and propellant components) and
partiallyinert ammunition of several types are used for
test,training, and practice purposes. Dummy or drill
ammunition (completely inert) resembling serviceammunition in
appearance, size, and weight, mayinclude functioning components
that contain noexplosive or propellant. It is used for training and
testpurposes. Cutaway ammunition (completely inert) hasa section
cut away to show inner construction andcomponents; it is used for
training and display purposes.Plaster-loaded or sand-loaded
ammunition lacks theexplosive burster charge but is otherwise not
inert; it isused for target practice and for testing of
launchers,mounts, or projectors.
As a member of a gun-loading crew, you will betasked with
finding, identifying, and loading differenttypes of ammunition.
Each round fired must beidentified and recorded in the ship's logs.
Ammunitionis identified by stenciled information printed on
theround and by its color. Stenciled information consistsmainly of
the Navy Ammunition Logistics Code(NALC)/Department of Defense
Identification Code(DODIC) and lot number.
A standard nomenclature and numbering system hasbeen established
by the Department of Defense (DOD).This system is a four-digit,
alphabetic/numeric codewhich will be either a Department of
Defenseidentification code (DODIC) assigned by DefenseLogistics
Services Center (DLSC) or a Navyammunition logistics code (NALC)
assigned by Ship'sParts Control Center (SPCC). Examples
ofDODIC/NALC nomenclature are as follows:
AMMUNITION TYPE DODIC/NALC
5"/54 Illumination Projectile D328
6"/50 BL&P Projectile D873
12 GAUGE 00 BUCKSHOT A011
COLOR CODES, MARKINGS, ANDLETTERINGS
The system of identifying ammunition by the use ofcolor codes,
marking, and lettering is intended to be a
ready identification to determine the explosive loadsand hazards
presented by the identified items. A colorcoding system is employed
to indicate the primary useof ammunition, the presence of a
hazardous (explosive,flammable, irritant, or toxic) filler, and/or
the color oftracers, dye loads, and signals. Information on
colorcoding for ammunition 20-mm or larger is contained
inMIL-STD-709, OP 2238 (latest revision), and WS18782. The
lettering, stenciled or stamped onammunition, includes all the
information necessary forcomplete identification and is marked in
with NATO standards and Department of Transporta-tion (DOT)
regulations. In addition to standardnomenclature and lot numbers,
lettering may includesuch information as the mark and mod, the type
offuzes, and the weapon in which the item is fired. Table6-1 gives
the meaning of the different color codes.
Gun ammunition is most commonly classified bythe size of the gun
in which it is used. In addition to
Gray with red band (s)
Gray with dark green band (s)
Table 6-1.Ammunition Color Coding
1. Identifies high explosives
2. Indicates the presence of explosive either
a. sufficient to cause the ammunition to function as a high
explosives orb. particularly hazardous to the user Brown
1. Identifies rocket motors2. Indicates the presence of
a. sufficient to cause the ammunition to funcuon as low
explosive orb. particularly hazardous to the user
Identifies ammunition that contains irritant or toxic agents
when used as an overallbody color except for underwater
Indicates the ammunition contains an irritant (harassing)
Indicates the ammunition contains a toxic agent
Identifies armor-defeating ammunition except on underwater
Identifies countermeasures ammunition
Identifies smoke or marker ammunition
Identifies incendiary ammunition or indicates the presence of
Identities illuminating ammunition or ammunition producing a
colored light;exceptions are underwater ordnance, guided missiles,
and rocket motors
Identifies ammunition used for training or firng practice
Identifies ammunition used for tracking or recovery
Identifies Dummy/Drill/Inert ammunition used for handling and
All ammunition items
1. For lettering
2. For guided missiles and rocker motors
designations of bore diameter, such as 20-mm, 3-inch,or 5-inch,
the length of the gun bore in calibers is alsoused as a means of
classification. Thus a 3-inch,50-caliber projectile is one used in
a gun having a borediameter of 3 inches and a bore length of 50
times 3inches, or 150 inches. The three types of
ammunitionclassified by assembly are shown in figure 6-1.
The Fixed class of ammunition applies toammunition that has the
cartridge case crimped aroundthe base of the projectile. The primer
is assembled in thecartridge case. The projectile and the cartridge
case,containing the primer and propellant charge, form oneunit as a
fixed round of ammunition. Small-caliber gunsand guns through
3-inch, 50-caliber use fixedammunition.
Semi-fixed, or separated ammunition, applies toammunition that
consists of two units: the projectileassembly and cartridge case
assembly. The projectileassembly consists of the projectile body
containing theload, the nose fuze, the base fuze, and the
auxiliarydetonating fuze, as applicable. The cartridge caseassembly
consists of the cartridge case, primer,propellant charge, wad,
distance piece, and a plug toclose the open end of the cartridge
ammunition is produced in gun sizes of 5-inch,54-caliber through
8-inch, 55-caliber guns.
The projectile is that component of ammunitionthat, when fired
from a gun, carries out the tacticalpurpose of the weapon. While
some types of projectilesare one piece, the majority of naval gun
projectiles areassemblies of several components. All of the
projectilesbriefly discussed by classification in this chapter
haveseveral common features, as described in the
followingparagraphs and as illustrated in figure 6-2.
The ogive is the curved forward portion of aprojectile. The
curve is determined by a complexformula designed to give maximum
range and accuracy.The shape of the ogive is generally expressed by
statingits radius in terms of calibers. It may be a combinationof
several arcs of different radii.
The bourrelet is a smooth, machined area that actsas a bearing
surface for the projectile during its travelthrough the bore of the
gun. Some projectiles have onlyone bourrelet (forward); the
rotating band serves as thebearing surface in the rear. Other
projectiles have onebourrelet forward and one or two aft, the after
one beinglocated adjacent to and either forward or aft of
therotating band. Bourrelets are painted to prevent rusting.
The body is the main part of the projectile andcontains the
greatest mass of metal. It is made slightlysmaller in diameter than
the bourrelet and is given onlya machine finish.
Figure 6-1.Types of gun ammunition: fixed (top);
semi-fixed(center); and separate-loading (bagged gun) (bottom).
Figure 6-2.Typical projectile, external view.
The rotating band is circular and made ofcommercially pure
copper, copper alloy, or plasticseated in a scored cut in the after
portion of the projectilebody. For all minor- and medium-caliber
projectiles,rotating bands are made of commercially pure copper
orgilding metal, which is 90-percent copper and10-percent zinc.
Major-caliber projectile bands are ofcupro-nickel alloy, containing
2.5-percent nickel ornylon with a Micarta insert. As a projectile
with ametallic band passes through the bore of the gun, acertain
amount of copper will be wiped back on therotating band and will
form a skirt of copper on the afterend of the band as the
projectile leaves the muzzle of thegun. This is known as fringing
and is prevented bycutting grooves, called cannelures, in the band
or byundercutting the lip on the after end of the band. Thesecuts
provide space for the copper to accumulate. Theprimary functions of
a rotating band are (1) to seal theforward end of the gun chamber
against the escape ofthe propellant gas around the projectile; (2)
to engagethe rifling in the gun bore and impart rotation to
theprojectile; and (3) to act as a rear bourrelet on
thoseprojectiles that do not have a rear bourrelet.
The base is the after end of the projectile. Aremovable base
plug is provided in projectiles that areloaded through this end. A
fuze hole may be drilled andtapped in the center of the base plug.
Projectiles withlarge openings in the nose for loading through that
endrequire no base plug. In such cases, however, the solidbase of
the projectile may be drilled in the center toreceive a base fuze
or tracer if desired. The edge formedby the side walls and the base
is usually broken slightlyto give additional range. Some
projectiles are tapered aftof the rotating band, a shape known as
boat-tailed.Projectiles with plastic bands may have full
caliberboat-tails for optimum aerodynamic shape.
Projectiles are also classified by their tacticalpurpose. The
following are descriptions of some of thecommon projectile types
ANTIAIRCRAFT (AA).Antiaircraft projectilesare designed for use
against aircraft; they have no basefuzes. Otherwise, they are
substantially the same as thehigh-capacity (HC) projectiles
ANTIAIRCRAFT COMMON (AAC).Antiair-craft common projectiles are
dual-purpose projectilescombining most of the qualities of the
AA-type with thestrength necessary to penetrate mild-steel
plate(fig. 6-3, view A). However, AAC projectiles do nothave the
penetrating ability of common projectiles. Thetype of fuzing will
depend on the use. Fuze threads areprovided in the nose and in the
base. AAC projectilesare normally equipped with a mechanical time
fuze(MTF) and an auxiliary detonating fuze (ADF).Dual-purpose
action is accomplished by a time settingfor air burst or by setting
MTFs on safe or for a timelonger than flight-to-target to permit
the base detonatingfuze (BDF) (delay) to function for penetration.
Bysubstituting a point detonating fuze (PDF) for the MTF,you can
convert these projectiles to high-capacity forsurface burst.
CHEMICAL.Chemical projectiles may be loadedwith a toxic,
harassing, or smoke-producing agent. Ofthe smoke agents, white
phosphorous (WP) is the mostfrequently used. WP projectiles (fig.
6-3, view B) aredesigned to produce heavy smoke and, secondarily,
anincendiary effect. The small WP containers are expelledand then
scattered by a delayed action burster chargethat is ignited by a
black powder expelling charge. Otherchemical loads are dispersed in
a similar manner.
PUFF.Puff projectiles (fig. 6-3, view C) arenonexplosive
projectiles used as practice (spotting)rounds. They are designed to
produce dense smokeclouds approximating those of high-explosive
DRILL.Drill projectiles are used by gun crews forloading drills
and for testing ammunition hoists andother ammunition-handling
equipment. They are madeof economical, but suitable metals, and are
designed tosimulate the loaded service projectile represented
insize, form, and weight. They may be solid or hollow. Ifhollow,
they may be filled with an inert material to bringthem to the
desired weight. This latter type is closed witha base or nose plug
or both, as appropriate.
DUMMY.Dummy projectiles are reproductionsof projectiles that may
be produced from a variety ofmaterials for a number of purposes.
Drill projectiles aredummy projectiles in that they are not to be
fired froma gun; however, all dummy projectiles are not
drillprojectiles. Dummy projectiles may be made fordisplay,
instruction, or special tests.
HIGH CAPACITY (HC).High-capacity pro-jectiles are designed for
use against unarmored surfacetargets, shore installations, or
personnel. They have amedium wall thickness and large explosive
Figure 6-3.Common projectile types.
Large HC projectiles (fig. 6-3, view D) are providedwith an
auxiliary booster to supplement the boostercharge in the nose of
the main charge. With threads inboth the nose and base, HC
projectiles may receive avariety of fuzes or plugs to accomplish
different tacticalpurposes. An adapter ring (or rings) is provided
on thenose end of most HC projectiles to allow installation ofpoint
detonating fuses (PDFs) or nose plug and auxiliarydetonating fuses
(ADFs) with different size threads. Anadapter is removed for larger
fuzes. HC projectiles are
normally shipped with a PDF installed in the nose. Thebase fuzes
that are shipped installed in the projectile maynot be removed
except at an ammunition depot.
ILLUMINATING (ILLUM). Illuminatingprojectiles (fig. 6-3, view E)
are made with thin walls.Each contains a time fuze, an ADF, a small
black powderexpelling charge behind the ADF, an assemblyconsisting
of a pyrotechnic star or candle with aparachute, and a lightly held
base plug. The time fuzeserves to ignite the expelling charge.
Explosion of the
expelling charge forces out the base and the
illuminatingassembly, and ignites the star or candle.
VARIABLE TIME NONFRAGMENTING(VT-NONFRAG). VT-NONFRAG
projectiles(fig. 6-3, view F) are loaded to avoid rupturing the
bodyand spreading fragments when the fuze functions;however,
sometimes the projectile ogive breaks up intolow-velocity
fragments. They are designed for use inantiaircraft target
practice, particularly againstexpensive drone targets, for
observing the results offiring without frequent loss of the drones.
Theseprojectiles have fillers of epsom salts or other inertmaterial
to give the projectile the desired weight. Acolor-burst unit,
consisting of pellets of black powderand a pyrotechnic mixture, is
placed in a cavity drilledin the center of the inert filler. The
color burst is ignitedthrough the action of the nose fuze and the
black-powderpellets. The color-burst unit may be one of several
colorsthat exits through the fuze cavity and ruptured
Propelling charges are mixtures of explosivesdesigned to propel
projectiles from the gun to the target.In fixed ammunition, the
propelling charge andprojectile are assembled together in a case
and handledas one unit; the principal component parts are the
brassor steel cartridge case, the primer, and a smokelesspowder,
the propelling charge. In the separatedammunition, the propelling
charges and projectile areassembled separately; they are stored and
handled asseparate units until they are loaded into the gun.
Thepropelling charge of the separated ammunition roundconsists of
the propellant primer, details, and closureplug assembled into the
metal case. The propellingcharges of separate loading ammunition
are made up insections (bag charges) separate from the projectile
andprimer. Propelling charges for all calibers ofammunition have
some common features. There are twobasic categories into which
these features can begrouped: case ammunition and bag charges.
Saluting,reduced, and clearing charges have components that arethe
same as case ammunition, so they are included withcase
Propelling charges for small- and medium-caliberguns are
assembled with primer and powder enclosed ina brass or steel
container, called a cartridge case(fig. 6-4, view A). Assembly of
the entire charge in asingle, rigid, protective case increases the
Figure 6-4.Propelling charges.
rapidity of loading and reduces the danger of flarebacks.Also,
the case prevents the escape of gases toward thebreech of the gun;
it expands from the heat and pressureof the burning powder and
forms a tight seal against thechamber.
A reduced charge is one in which less than theservice load of
powder is placed in the cartridge case.Reduced charges may be used
in target practice, todecrease the wear on the gun.
When a round fails to seat fully upon being rammedinto the gun
chamber, thus preventing closure of thebreech, or when the
propelling charge fails to function,the projectile may be fired by
extracting the full-sizedcase and loading a shorter clearing
Saluting charges are charges used when firing a gunto render
honors. Since no projectile is involved in suchfiring, the charge
consists of a cartridge case containinga black powder load and a
primer. The ships normallyemploy 40-mm or 3-inch guns for saluting.
charges for the 40-mm and the 3-inch guns are issuedcompletely
assembled, with no replacementcomponents.
In large guns (8-inch) using separate loadingammunition, the
propellant charge is made up ofsections of powder contained in
cylindrical cloth bagsthat approximate the inside diameter of the
gun chamberin which they are to be used. In most cases, more
thanone section (bag) is required. For example, the
8-inch,55-caliber gun uses a propellant charge consisting oftwo
sections; the 16-inch, 50-caliber gun uses apropellant charge of
six sections (fig. 6-4, view B). Inthese guns the leaking of gases
from the chamber ischecked by the mushroom and pads on the breech
plug.The breech plug also contains a lock, which receives
theseparately loaded primer.
Fuzes are the components that set off the projectilebursting
charge. No matter how complicated or simplethe construction or
function of the fuzes, they alwaysserve the same purpose.
All fuzes use the force of inertia for arming and, inmost cases,
operation. Each type of fuze has a differenttactical use. The use
and a detailed functionaldescription will not be covered in this
text. For moreinformation on ammunition types and their fuzes,
referto Navy Gun Ammunition, SW030-AA-MMO-010.
Fuzes can be generally classified by function, asdiscussed in
the following paragraphs.
TIME FUZES.Mechanical time fuzes (MTFs)function a predetermined
length of time after theprojectile is fired. The exact time is set
before theprojectile is loaded into the chamber, by a
mechanicalfuze setter on the mount, or you can set the fuze with
aspecial fuze wrench. The interval between the instantthe fuze is
set and the instant the projectile is fired isdead time. No matter
when, how, or by what it is set, thetiming mechanism of a time fuze
will not function untilthe projectile is fired.
PROXIMITY FUZES.Proximity (variable time(VT)) fuzes are
energized after the projectile is fired andfunction when the
projectile nears the target.
PERCUSSION FUZES.Percussion (impact)fuzes function as the
projectile strikes the target or(especially an armor-piercing
projectile) after theprojectile penetrates. Some fuzes (nondelay
function immediately on contact with any thin material(for
example, the thin sheet metal skin of an aircraft).Fuzes for
armor-piercing projectiles, however, alwaysincorporate a slight
delay to keep the burster from goingoff until after penetration.
These percussion fuzes canbe located either on the nose (PDF) or on
the base (BDF)of the projectile.
COMBINATION FUZES.Combination fuzesincorporate both time and
percussion features; that is,the fuzes may go off either on impact
or after the timeset, whichever occurs first.
AUXILIARY DETONATING FUZES.Auxiliary detonating fuzes (ADF), as
the name implies,operate only with other fuzes. In gun projectiles,
theyform part of the explosive train and pass on theexplosion
initiated by another fuze (located in theprojectile nose) to the
main bursting charge.
The term magazine applies to any compartment,space, or locker
that is used or is intended to be used forthe stowage of explosives
or ammunition of any kind.
The term magazine area includes the compartment,spaces, or
passages on board ship that contain magazineentrances and that are
intended to be used for thehandling and passing of ammunition. The
term is alsoused to denote areas adjacent to, or
surrounding,explosive stowages, including loaded
ammunitionlighters, trucks, and railroad cars, where
applicablesafety measures are required.
Magazines are arranged with regard to ease ofsupply, the best
obtainable protection, and the mostfavorable stowage
Many different types of magazines are provided onships. Each
magazine is designed specifically for thetype of ammunition it is
to contain. For our purpose,however, we will be concerned with only
three types:primary magazine, ready-service magazine,
PRIMARY MAGAZINES.Primary magazinesare designed as ammunition
stowage spaces generallylocated below the main deck and, if
possible, below thewaterline. They are adequately equipped
withinsulation, ventilation, and sprinkler systems. Thesespaces
must be provided with fittings so that they maybe securely locked.
Primary magazines accommodate a
vessel's complete allowance of ammunition forpeacetime
READY-SERVICE MAGAZINES.Ready-service magazines are spaces
physically convenient tothe weapons they serve. They provide
permanentstowage for part of the ammunition allowance. They
arenormally equipped with insulation, ventilation, andammunition
sprinkler systems, and should be securedby locking. The combined
capacities of primary andready-service magazines are normally
sufficient to stowproperly the allowance for war and
READY-SERVICE STOWAGE.Ready-servicestowages are those ammunition
stowage facilities in theimmediate vicinity of the weapon served.
They includeweather deck lockers, bulwark (gun shield) racks,
and5-inch upper handling rooms. This stowage normally isfilled only
when the weapon is to be fired. There is littlesecurity for
ammunition in such stowage, and it providesthe least favorable
protection from the elements.
Magazine Sprinkler Systems
As a member of a magazine crew, you may betrained to operate the
magazine sprinkler systemsprotecting your magazine. You must be PQS
qualifiedto operate any sprinkler system. Do not tamper with
anysprinkler system controls unless you have beenthoroughly
trained, certified, and instructed to do so bycompetent authority
according to your ship'sinstructions.
Sprinkler systems are used for emergency coolingof, and
firefighting in, magazines, ready-service rooms,ammunition, and
missile-handling areas. A magazinesprinkler system consists of a
network of pipes securedto the overhead and connected by a
sprinkler systemcontrol valve to the ship's saltwater firemain. The
pipesare fitted with spray heads or sprinkler head valves thatare
arranged so that the water forced through themshowers all parts of
the magazine or ammunition andmissile handling areas. A modern
sprinkler system canwet down all exposed bulkheads at the rate of 2
gallonsper minute per square foot and can sprinkle the deck areaat
the rate of 4 gallons per minute per square foot.Magazine sprinkler
systems are designed so that theyare capable of completely flooding
their designatedspaces within an hour. To prevent unnecessary
floodingof adjacent areas, all compartments equipped withsprinkler
systems are watertight. Upper deck handlingand ready-service rooms
are equipped with drains thatlimit the maximum water level to a few
inches.Magazines are completely enclosed; if flooded, they
would be exposed to the full firemain pressure. Thefiremain
pressure on most ships is considerably higherthan the pressure that
magazine bulkheads couldwithstand; therefore, magazines are
equipped withexhaust ventilators, which are located in the
bulkheadnear the overhead. An exhaust ventilator is a pipe witha
check valve that permits pressure release (usually tothe topside).
Since the diameter of the pipe is largeenough to allow water to
flow out as fast as it flows in,no excess pressure can build up in
Magazines are also equipped with small, cappeddrainpipes located
in the bulkhead near the deck Thecaps may be removed in the
adjacent compartment todrain flooded magazines.
The sprinkler system control valve and associatedcomponents vary
in complexity with the type of ship,type of stowage, and type of
ammunition or missilestowed in the magazine.
LEARNING OBJECTIVE: De f inepyrotechnic. List and explain the
different typesof pyrotechnics pistols and pyrotechnics usedaboard
ship. Explain the storage and handlingprocedures for
Pyrotechnic is the Greek word for fireworks. TheNavy uses
fireworks not for celebration but forillumination, marking, and
signaling. An example is theilluminating projectile, or star shell,
used to illuminatetargets for gunfire. A star shell actually is a
pyrotechnicdevice, although it is encased in a projectile body
ofstandard external shape and is fired from a standardrifled
In the following sections, we discuss the commonpyrotechnic
devices currently in use on modern Navysurface ships. For further
information on these and otherpyrotechnic devices used by the Navy,
refer toPyrotechnic, Screening, Marking, and CountermeasureDevices,
NAVSEA SW050-AB-MMA-010. All thepyrotechnics we study here are
intended for signalingand marking. We discuss the following:
Marine location markers
Marine illumination signals and the pyrotechnicpistols and
projectiles used in firing them
Also, at the end of this section on pyrotechnics, weprovide some
basic information on the proper handlingand storage of these
MARINE LOCATION MARKERS
Marine location markers are used as night or daylong-burning
reference markings on the ocean's surface.They are dropped over the
side from surface ships forman-overboard marking, navigation
drills, and othersimilar operations. These markers may also be
droppedfrom aircraft for search and rescue operations. The
twomarine location markers currently in use are the Mk 58and the Mk
Mk 58 Marine Location Marker
The Mk 58 marine location marker is the primarymarine location
marker found aboard surface vessels. Itis approximately 21 1/2
inches long and weighs about12 3/4 pounds. It contains a battery
squib, some startermix, two pyrotechnic candles, and a transfer
fusebetween the two candles. Before launching, the tear tapeover
the water port must be removed so that seawatercan enter to
activate the battery. Battery currentenergizes the electric squib,
which ignites the starter
mix, which, in turn, lights the pyrotechnic candle. Whenthe
first candle has burned out (in 20 to 30 minutes), thesecond candle
is started by the transfer fuse, for a totalburning time of
approximately 40 to 60 minutes. TheMk 58 currently is available in
two versions: the Mod0 and the Mod 1. The Mod 0 is a hermetically
sealedcan, which is opened with a twist key. Figure 6-5illustrates
this marker. The Mod 1 (fig. 6-6) is cappedwith a replaceable
MK 6 Marine Location Marker
The Mk 6 aircraft smoke and illumination signal(fig. 6-7) is a
pyrotechnic device that is launched fromsurface craft only to
produce a day or night floatingreference point. One of its
principal uses is as aman-overboard marker. It was previously
approved forlaunching from low-performance aircraft as
along-burning marker but has been replaced for thispurpose by the
Mk 58 marine location marker.
The Mk 6 signal consists of a wooden body with aflat, die-cast
metal plate affixed to one end to protect itfrom water impact
damage and to maintain it in thecorrect floating attitude. There
are four flame and smokeemission holes in the opposite end, each
Figure 6-5.The Mk 58 Mod 0 marine location marker.
Figure 6-6.The Mk 58 Mod 1 marine location marker.
sealed with tape. The pull-wire ring, also at the emissionend,
is also covered with tape.
The Mk 6 signal has a direct-firing ignition system.Ignition
results from pulling the pull ring. The pull ringis pulled by hand,
and the device is thrown into the waterimmediately. The pull wire
ignites a 90-second delayfuse that ignites the quick match at the
top of the first offour candles. The quick match ignites the first
candlestarting mix, which, in turn, initiates burning of
thatcandle. Expanding gases of combustion force the capand tape
from the emission hole, allowing smoke andflame to be emitted. When
the first candle is nearlyburned out, a transfer fuse carries the
ignition to thequick match of the next candle in series. This
processcontinues until all four candles have burned. The
yellowflame and gray-white smoke are produced for at least
After the tear-strip on the shipping container hasbeen removed,
the following rules apply:
1. The tape over the pull ring should not bedisturbed until
immediately before hand-launching thesignal. This tape not only
prevents an accidental pull onthe pull ring but also protects the
igniter assembly frommoisture, which might render the signal
This signal is initiated by the physicalmovement of a friction
wire through ignitioncompound. Extreme care must be taken toprevent
tension of the pull ring during allhandling operations.
2. If this device is prepared for launching and is notlaunched,
the pull ring should be securely retaped intoposition at the top of
the signal without exerting anypulling force on the pull-wire
3. Under no circumstances should these signals bestowed or
restowed with their pull rings exposed or withany wires, strings,
or other material of any kind joinedto their pull rings.
All safety precautions pertaining to this signal mustbe
observed. In addition, the following specific rulesapply:
Do not remove the tape over the pull ring untilimmediately
The Mk 6 signal should be thrown over the sideimmediately after
pulling the pull ring. This device
Figure 6-7.The Mk 6 Mod 3 marine location marker.
contains a maximum 90-second delay element between Man-overboard
and navigation drills are good instances
initiation and candle ignition. where these stocks can be
In all handling, extreme care should be takento avoid pulling on
the pull ring. The slightest
MARINE ILLUMINATION AND SMOKE
movement of the friction igniter may start the ignitionSIGNALS
AND PYROTECHNIC PISTOLS
The Mk 6 Marine Location Marker is being replacedby the Mk 58.
There are, however, remaining serviceablestocks of the Mk 6
available. If you have any of thesemarkers in your inventory, they
should be used first.
Marine illumination signals are similar in appear-ance to a
standard shotgun cartridge. When fired fromthe proper pistol or
projector, a burning star (somewhatlike a star from a roman candle)
shoots high into the air.In this section, we describe the marine
smoke signals and pyrotechnic pistols currently in use.These
Mk 2 marine illumination signal,
Mk 5 pyrotechnic pistol,
AN-M37A2 through AN-M39A2 series, double-star illumination
Mk 1 marine illumination signal, and
the AN-M8 pyrotechnic pistol.
MK 2 Marine Illumination Signals
The Mk 2 marine illumination signal is available inthree colors:
red, green, and white. Each cartridge hasa percussion primer and a
propelling or expelling chargeof 10 grains of black powder, which
projects the burningstar to a height of about 200 feet. The star
charge is atightly packed cylinder wrapped with a quick match
(afast-burning fuse), which ignites it when fired. The starcharge
is separated from the expelling charge by ashock-absorbing wad of
hard felt. The cartridge isclosed by a wad that is so marked that
the color of thestar can be determined at night by feeling the wad,
asshown in figure 6-8.
The red star may be identified by its corrugatedclosing wad; the
green star has a smooth closing wad;and the white has a small
conical boss on its closing wad.Each of the three colors may also
be identified by thecorresponding color of the paper on the
The burning time for each of the stars is approxi-mately 6
The illumination signals are available in 10-roundmetal or
cardboard containers. The containers arepackaged in wooden boxes
that hold 40, 45, or 100containers.
Mk 5 Pyrotechnic Pistol
Marine illumination signals are fired from the Mk 5pyrotechnic
pistol. This pistol is a breech-loaded,double-action, single-shot
device, 11 inches long. Metalparts are mounted on a plastic frame.
The operatinginstructions for the Mk 5 pistol are as follows:
1. To load the pistol, depress the latch button belowthe barrel.
At the same time, pull the barrel downward,as in view A of figure
6-9. Insert the signal shell (viewB). Push the barrel upward until
it latches closed. Thepistol is now ready to fire.
Figure 6-8.The Mk 2 marine illumination signal.
Figure 6-9.Operation of the Mk 5 pyrotechnic pistol.
2. To fire the pistol, aim it upward at the desiredangle,
normally 60 degrees, but clear of other ships orpersonnel. Bull the
trigger, as shown in figure 6-9, viewC. Keep your elbow slightly
bent when firing, to absorbthe shock of recoil and to prevent the
pistol fromknocking itself out of your hand.
3. To extract the expended shell, break the pistolopen again
(view A), and pull the shell out of thechamber (view D).
The pyrotechnic pistol is cocked at all timeswhen the breech is
closed; it has no positivesafety mechanism. Illumination signals
mustNOT BE LOADED in the pistol until justbefore use. Unfired
signals must NOT be left inthe pistol.
The Mk 5 pistol must be kept in serviceablecondition at all
times. Clean it thoroughly after each usein accordance with the
procedure prescribed on theappropriate 3-M System maintenance
When loading or firing a pyrotechnic pistol,NEVER point it in
the direction of other personnel orvessels.
NEVER use the Mk 5 pistol with ammunition otherthan that
authorized for use with it. Conversely,illumination signals should
never be fired from shotgunsor from projectors other than those
PYROTECHNIC SAFETY HANDLING ANDSTORAGE
The following general information is taken directlyfrom
Pyrotechnic, Screening, Marking, andCountermeasure Devices, NAVSEA
SW050-AB-MMA-010, chapter 1.
All pyrotechnic and screening devices, whiledesigned and tested
to be safe under normal conditions,can be subject to accidental
ignition because of a widevariety of circumstances. The general
rule to follow is:Be constantly aware that pyrotechnics contain
chemicalcomponents that are intended to burn with intense heat,and
Pyrotechnic Handling and Storage
All pyrotechnics and smoke-screening devices aredesigned to
withstand normal handling. They should,however, be handled as
little as possible to lessen thechances of damage, which might
cause accidentalignition or leakage. Many devices contain materials
ofa dangerous nature and are therefore designed withsafety
features, which should be maintained in goodoperating condition.
Dents, deformations, or cracks inthe outer body may interfere with
the proper functioningof these safety features or might cause
handling or storage. It is therefore imperative thatextreme care
be taken to prevent damage to containersof pyrotechnics and
screening devices, and to thedevices themselves.
Effect of Moisture on Pyrotechnics
The proper functioning of pyrotechnic, dye-marking, and
screening devices is frequently affected bymoisture. Some
compositions may become moresensitive and dangerous when exposed to
moisture,while others tend to become difficult to ignite and
lessdependable in operation. Care should be exercised toprevent
damage that would interfere with seals becausesome screening
devices produce their smoke by reactionof their chemical contents
with moisture in the air. Also,bear in mind that some marine
location markers, suchas the Mk 58, are saltwater-activated, and
should bestored with that in mind. That fact should also
beconsidered in emergency situations where the markerscould be
inadvertently exposed to fire-fighting water orrunoff.
Effect of Temperature on Pyrotechnics
Pyrotechnics and some screening devices maybecome adversely
affected by excessively high orvariable temperatures. These devices
should never bestored where direct rays of the sun could
generateexcessively high temperature. Storage should be in
dry,well-ventilated places that provide the greatest
possibleprotection from such conditions. All Navy pyrotechnicshave
been designed to withstand temperatures from-65F to 160F and,
therefore, will probably be safefrom deterioration or damage within
that range.However, it is recommended that every reasonableeffort
be made to maintain storage temperature at notmore than 100F.
(Specific ammunition storagetemperature requirements are addressed
in chapter 2 ofthis manual.)
Toxic Hazards of Pyrotechnics
Many chemicals used in pyrotechnics, screeningequipment, and
dye-marking devices are poisonous iftaken internally. This also
applies to the residue ofburned pyrotechnics. From the inhalation
standpoint,the products of pyrotechnic devices and smokegenerators
often present a serious problem. Many of thesmokes and fumes given
off by pyrotechnics andscreening devices are considered non-toxic
and onlymildly irritating to the eyes and nasal passages
whenencountered in relatively light concentrations out of
doors. Heavy concentrations in closely confined spaces,however,
are dangerous and may be lethal because theyreduce the amount of
oxygen in the air. Anything morethan a brief exposure to the gases
of combustion, or toscreening smokes, should be avoided or should
beprotected against through the use of an appropriatebreathing
ORDNANCE HANDLING SAFETY
LEARNING OBJECTIVES: Recognize safetyprecautions, practices, and
principlesapplicable for the handling of ordnance. Listgeneral
ammunition safety precautions. Listand define standard commands for
The utmost care and prudence must be exercised insupervising the
handling, inspecting, preparing,assembling, and transporting of all
types of ammunition.People tend to become careless and indifferent
whencontinually engaged in work with explosives and, aslong as
nothing occurs, are inclined to drift graduallyinto neglecting the
necessary precautions. Nothing butconstant vigilance on the part of
the all concerned willensure the steadfast observance of the rules
andregulations that experience has taught are necessary.
Safety is everyone's responsibility. Awareness ofdanger,
knowledge of how danger can be avoided, andconstant vigilance are
the three basic requirements toprevent accidents when working with
explosives. If athorough understanding of the basic ideas behind
theprecautions is developed, unsafe conditions can berecognized and
corrected and further suitable actiontaken instinctively when the
unexpected occurs. Safetyprecautions pertaining to the handling of
and workingwith explosives may be found in OP 4, AmmunitionAfloat;
OP 1014, Ordnance Safety Precautions, TheirOrigin and Necessity;
and OP 3347, United StatesOrdnance Safety Precautions.
Safety precautions, rules, and regulations forhandling
explosives should be made the subject offrequent review, and the
necessity for strict compliancewith these precautions should be
firmly fixed in theminds and habits of all hands involved in
handlingexplosives so that they will react in an emergency to
theinstruction previously received.
Note that in the early stages of the use of
explosives,experience was gamed at a great pricenot only indollars,
but in human lives. No relaxation should betolerated, since this
tends to create the impression thatthe rules are arbitrary.
All personnel assigned to handle ammunition orgunnery equipment
should receive a thoroughindoctrination from a qualified chief
petty officer orpetty officer regarding the general safety
precautionsand procedures to be followed in the course of
theirduties. This indoctrination is MANDATORY beforeANY
Periodic drills should be conducted to providerealistic training
and to identify and/or eliminate anyunsafe practices. Inexperienced
personnel willconstantly be under the direct supervision of skilled
andexperienced personnel until adequate experience isacquired.
Because of the nature of gunnery and ammunition,safety
precautions should be of extreme importance toevery Seaman.
Compliance with all safety procedureswill ensure a safe ammunition
The following general safety precautionsconcerning gunnery and
ammunition should be ofextreme importance to every Seaman:
Ammunition should ALWAYS be handled carefullyand ONLY when
The proper way to handle ammunition is to hold thebase of the
projectile downward with one handcovering the base, while
supporting the top of theround up at a 45 angle and cradling the
top, like ababy, in the elbow.
Smoking is prohibited in magazines and any areacontaining
explosives or ammunition, as well as inthe vicinity of handling or
loading operationsinvolving ammunition.
Naked lights, matches, lighters or other spark-,flame-, or
heat-producing devices should NEVERbe taken or stowed near
magazines or any other areawhere explosives are present.
Unauthorized personnel should not be permitted inmagazines or in
the vicinity of handling operationsinvolving explosives or
Personnel assigned to gunnery stations duringgeneral quarters
should ALWAYS know the type ofammunition being handled.
Ammunition handlers should wear appropriateclothing and safety
shoes. Ammunition handlersshould never wear keys, gloves, rings,
watches, orheadgear when handling ammunition. Belt bucklesshould be
turned inside or be removed to avoid thepossibility of striking a
primer on a projectile.
Fire hoses should be laid out and charged beforehandling weapons
as well as gunnery exercises, andrepair lockers should be manned
and ready asappropriate.
When guns are trained or elevated, an audiblewarning alarm is
sounded from within the gunenclosure. All hands should stand
outside the trainwarning circle.
No ammunition or explosive assembly may be usedin any gun system
for which it is not designed.
Powder cans and bags must always be in perfectcondition.
Care must be taken to avoid obliteratingidentification marks on
ammunition or putting itinto incorrectly marked containers.
Smokeless powder must never be exposed to thedirect rays of the
sun. Powder in bulk, tanks,cartridge cases, ammunition boxes, and
othercontainers must be protected against hightemperature.
Smokeless powder, when wet, must be regarded asdangerous for dry
storage and must be keptimmersed completely in freshwater. It must
beturned in at an ammunition depot at the first chanceor dumped
Before any work that may cause either anabnormally high
temperature or an intense localheat in a magazine is started, all
explosives must beremoved to safe storage until normal conditions
Pyrotechnic material must always be kept by itselfin regular
pyrotechnic lockers or storage spaces.
Black powder, which is most dangerous, mustalways be kept by
itself. Containers of black powdermust never be opened in a
magazine or adjacent toother explosives.
Projectiles must not be altered, nor may fuzes orother parts be
removed from them on board shipwithout instructions from higher
A fuzed projectile or a cartridge case, whether in acontainer or
not, if dropped from a height exceeding5 feet, must be set aside
and turned in at anammunition depot as soon as possible.
Suchammunition must be handled with the greatest care.
Service ammunition is never used for drill; only drillammunition
may be used.
Certain fuzes armed by setback may explodeaccidentally by
tapping or jarring. Extreme caremust be taken to avoid dropping
Care must be taken that nose fuzes are not struck (asby the gun
Time fuzes that have been set must be reset on SAFEbefore
LEARNING OBJECTIVES: Define gunmount. Identify the different
components of agun mount.
A gun mount is the supporting structure assemblyand operating
device for one or several guns. Themounts may be open, or enclosed
in a shield. Eachmount is assembled as a unit by the manufacturer,
thenhoisted on board ship and bolted in place.
Modern gun mounts have been effectivelydeveloped to meet the
threat of all types of targets. Theycomprise an entire system of
gun-supporting parts thatenable them to rapidly load, position, and
fire theirprojectiles with such speed and accuracy that they
havebecome the backbone of the U.S. Navys support forces.
Every gun system includes equipment used for gunpositioning,
loading, and firing. Loading equipmentvaries greatly in design from
gun to gun, but its purposeremains the sameto load a complete round
in the gunchamber for firing. We will describe the various
loadingsystems later in this chapter. The greatest similaritiesfrom
one gun to the next are found in the positioningand firing
components, which we will now describe.
Positioning equipment includes all the machineryused to support
and move the gun tube to the desiredtrain (horizontal) and
elevation (vertical) angle.Positioning equipment includes the
stand, base ring,trunnions, carriage, and slide, (fig. 6-10).
The stand is a steel ring bolted to the deck; it servesas a
foundation and rotating surface for movement intrain. The stand
contains both the train beatings and thetraining circle. The
training circle is a stationary internalgear that the train drive
pinion walks around to movethe gun in train.
Figure 6-10.Gun-positioning equipment.
The base ring is also called the lower carriage. It isthe
rotating platform, supported by the stand, andsupports the upper
Gun Carriage and Trunnion Bearing
The gun carriage is also called the upper carriage.It is a
massive pair of brackets that holds the trunnionbearings. The
trunnion bearings support the trunnions,which are part of the
slide; together they form theelevation pivot point.
The slide is a rectangular weldment that supports allof the
elevating parts of the gun.
Firing equipment includes all the componentsnecessary to allow
the gun to safely fire, absorb theshock of recoil, and reposition
for further firing. Thisincludes the housing, breechblock, recoil,
counter-recoilsystems, firing circuits, and firing cutouts.
Figure 6-11.The sliding-wedge breechblock.
The housing is a large steel casement in which thebarrel and
breechblock are fitted. The housing moves inrecoil inside the
The breechblock seals the breech end of the barrel.The
sliding-wedge-type breechblock (fig. 6-11) consistsof a machined
steel plug that slides in a grooved way inthe housing to cover the
breech opening. The groovesare slanted so that the breechblock
moves forward as itcovers the back of the casing, edging it in
place. All gunscurrently use the sliding-wedge-type
Normally, a recoil system (fig. 6-12) consists of twostationary
pistons attached to the slide, set in aliquid-filled cylinder in
the housing. As the housingmoves rearward in recoil, the trapped
liquid is forcedaround the piston head through metered
orifices,slowing the movement of the housing.
A counterrecoil system consists of a piston (orpistons) set in a
pressurized cylinder. As the gun recoils,the piston protrudes
further into the cylinder. After theforce of recoil is spent, the
air pressure, acting againstthe piston, pushes the housing back
into the battery (thefull forward position). The piston may be
attached to theslide, allowing the cylinder (which is machined into
thehousing) to slide over it during recoil (fig. 6-13). Laterguns
use two free-floating pistons set in an air chambermounted to the
inside of the slide (fig. 6-14). Air pressure
Figure 6-12.Recoil and counterrecoil system.
holds the pistons against the back of the housing, andforces
them into the stationary chamber during recoil.
Figure 6-13.A basic recoil and counterrecoil system.
Since the air pressure in the counterrecoil system isthe only
thing holding the gun in battery, all guns areequipped with a
safety link. The safety link physicallyattaches the housing to the
slide to prevent it frommoving if system pressure is lost. The
safety link isdisconnected prior to firing.
Basically, a firing circuit supplies firing voltage tothe
propelling charge primer. This sounds simple, butthe application
can be quite complicated. For a safe
Figure 6-14.5"/54 Mk 42 recoil and counterrecoil system.
evolution, certain conditions must exist prior to firing.Making
sure that the gun is pointed in a safe direction,that all the
loading equipment is in the fire position (outof the way of
recoiling parts), and that the breechblockis all the way closed are
just a few of the obvious thingsthat must be correct before firing.
A typical electronicfiring circuit includes inputs that monitor
these andmany other conditions, allowing firing voltage to passonly
after all safety conditions have been satisfied.
A firing cutout mechanism interrupts firing whenthe gun is
pointed at or near the ship's permanentstructure. A firing cutout
is a mechanical device thatmonitors gun position.
The components we have just described arecommon to all guns. We
will now discuss the individualgun systems in the fleet today,
paying particularattention to the loading system in each one.
LEARNING OBJECTIVES: List and explainthe different gun mounts
used aboard ship.Explain crew position and responsibilities
andloading sequence when operating gun mounts.
As you read this section and study the illustrations,note the
different configurations of machinery designedto accomplish the
same task from one gun to the next.When we are speaking of gun
equipment, all directionalnomenclature (left, right, front, back)
is relative to themuzzle of the gun (the end of the barrel from
which theprojectile exits when fired); the muzzle is to the front
asyou stand inside the gunhouse.
5"/54 MK 42 GUN
In the 1950s as potential targets became faster andmore
sophisticated, a gun with more range and a fasterrate of fire was
needed. The 5"/54 Mk 42 was developedto effectively engage these
targets as well as shoretargets. Several versions of the Mk 42 gun
have seenservice since then. In the fleet today, you will find
onlythe Mod 9 and the Mod 10; all others have been retired.The two
versions are identical in many respects. Thedifferences will be
pointed out at the end of this section.
The 5"/54 Mk 42 is an automatic, dual-purpose gunmount. It can
be controlled either remotely from a firecontrol system, usually
the Mk 68 GFCS, or locallyfrom the mount at the One Man Control
The normal mode of operation is the remote mode. Themount fires
an average 70-pound projectile up to 26,000yards with a 48,000-foot
ceiling. The gun, with itsautomatic loading system, has a rate of
fire of 34 roundsper minute.
As you will see, the loading system is actually twoalmost
separate systems, left and right. The ammunitioncarrier and the
hydraulic power drive units are the onlycomponents shared by both
sides. The advantage ofhaving separate systems is readily apparent.
In the eventof a casualty, you can isolate the affected side
andcontinue to fire at 17 rounds per minute from the otherside.
We will now describe the major components of themount as we walk
through a loading cycle.
Figure 6-15 illustrates the major components of the5"/54 Mk 42
gun. The gun is operated by the mountcaptain from the EP2 panel.
Electrical power is suppliedto the gun through the EP1 panel. Both
the EP1 and EP2panels are located in the compartment directly under
themount, along with the lower hoist power drive,ammunition
carrier, and upper hoists. This compartmentis commonly called the
carrier room. Inside the gunmount, there are two manned positions:
the gun captainand the OMC operator. The gun captain has
theresponsibility of monitoring the operation of the gun
andrelaying bore reports (whether or not the gun bore isclear)
after each round or salvo is fired. The OMCoperator functions as a
check sight observer duringnormal firing. As check sight observer,
he uses thetelescopic sight to ensure that the gun is trained on
theintended target. He then reports CHECK SIGHT ONTARGET. The
loader drums, located in the projectilemagazine, are served by the
magazine crew. Themagazine crew is made up of Seamen from
variousdivisions of the ship. You may be assigned to this
station.Here, you will remove propelling charges andprojectiles
from their storage bins and load them into theloader drums at the
command of the mount captain.Some individuals from the magazine
crew also serve asmembers of the hot gun clearing team.
Theresponsibilities of this team will be described later inthis
When a remote order is received, the mount captaingives control
of gun train, elevation, and firing circuitto the fire control
system. When ordered to fire, themount captain initiates the
loading cycle by pressingthe RAM ONCE or the RAM CONTINUOUS
buttonon the EP2 panel. RAM ONCE allows one round to beloaded and
fired. RAM CONTINUOUS allows the gunto continue firing until it is
empty or ordered to stop by
Figure 6-15.Major components of the 5"/54 Mk 42 (Mod 10
the mount captain, who presses the OFF button. In bothinstances,
the rounds are fired using firing voltagesupplied from the fire
control system. When firing iscontrolled from the OMC station, the
operator suppliesall the inputs normally received from the fire
controlsystem. The operator positions the mount with the OMCunit,
while aiming with the telescopic sight, then firesthe gun using
his/her own firing key. Note that the mount
captain has to physically give control of the mount tothe
5"/54 MK 45 GUN
The 5"/54 Mk 45 gun, developed in the early 1970s,is the newest
of the 5" guns in the fleet today. It is foundaboard the DD-963,
DDG-51, LHA-1, and CG-47 class
Figure 6-16.The 5"/54 Mk 45 Mod 0, general arrangement.
ships. The Mk 45 (fig. 6-16) is a fully automatic,dual-purpose,
lightweight gun mount capable of firingthe full range of 5"/54
projectiles, includingrocket-assisted projectiles (RAPs), at a rate
of 17 to 20rounds per minute. During normal operation the
loadingsystem (fig. 6-17), like the Mk 42, is operated locally
bythe mount captain; the gun laying, fuze setting, andfiring orders
are generated by the FCS. The gun may bepositioned locally from the
EP2 panel for maintenanceonly.
The only manned positions on the Mk 45 gun duringnormal
operations are the mount captain, who operatesthe gun from the EP2
panel, and the loader room crew.The gun mount itself, unlike the Mk
42, is unmanned.There is no local firing position, as with the Mk
OMC. The mount power distribution panel, EP1, is alsothe mount
The loader drum holds a total of 20 complete roundsof
ammunition. Before an operation, the loader crewwill load the drum,
through the lower hoist, with 20rounds of one type of ammunition.
If during theoperation another type of round is desired, the
mountcaptain, using local controls, can allow the system tooperate
under alternate loading. This mode allows theloaders to hand-feed
the different types of ammunitioninto the loading system, which
automatically transfersonly these rounds to the breech for firing.
Dependingupon the tactical situation, the loader crew may
berequired to load several different types of ammunitionin a short
time. The loader crew must, therefore, be able
Figure 6-17.The 5"/54 Mk 45 gun loading system, major
to quickly and accurately identify the variousammunition
76-MM MK 75 GUN
The Mk 75 gun (fig. 6-18) is a fully automated,remotely
controlled gun mount that stows, aims, andfires 76-mm 62-caliber
ammunition. The 76-mmsystem, along with the Mk 92 GFCS, is
currently aboardFFG-7- and PHM-class ships. The design of the
gunmount makes extensive use of lightweightcorrosion-resistant
alloys and modern engineeringtechniques. The result is a
lightweight, compact,fast-firing, versatile weapon. It is primarily
a defensiveweapon, used to destroy antiship cruise missiles.
However, it can also be used effectively against surfaceand
shore targets. The gun has a variable rate of fire ofup to 80
rounds per minute with a range of up to 16,459meters and a maximum
altitude of 11,519 meters. Themost notable innovation featured on
this system is theautomatic barrel cooling system. This cooling
systemallows sustained operation at high rates of fire
withoutexcessive barrel wear or the danger of a cookoff if amisfire
The Mk 75 gun fires a somewhat limited variety ofammunition
types. The types of ammunition currentlyavailable include point
detonating (PD), infrared (IR),radio frequency (RF), and
blind-loaded and plugged(BL&P).
Figure 6-18.The Mk 75 gun system, general configuration.
The gun mount crew consists of the mount captain,two loaders,
and the safety observer.
The mount captain is stationed in the ammunition-handling room
at the gun control panel (GCP). It is themount captain's
responsibility to set the gun up for thedesired mode of operation,
then monitor it, in case of amalfunction. In case of a malfunction
or misfire, themount captain supervises and directs the
The two loaders are stationed in the ammunition-handling room
during loading and unloading operations.Their primary duties are to
load and unload the gun, clearmisfires, and assist in corrective
maintenance. Althoughthe actual loaders may be Gunner's Mates
(GMGs), youmay be stationed in the handling room to assist in
breakingout the ammunition for loading.
The safety observer is stationed topside, near the gun.It is the
responsibility of the safety observer to monitor thegun and the
area around the gun for any unsafe condition.The safety observer is
in direct contact with the mountcaptain.
LEARNING OBJECTIVE: Define the duties ofa hot-gun crew.
As is true of all mechanical devices, guns, too, aresusceptible
to malfunctions. In the case of a gunsystem, however, you are also
dealing with largequantities of propellant and high explosives.
When agun misfires, either the casualty must be correctedquickly or
the round removed from the gun chamberand disposed of over the
side. A hot gun is a gun thathas fired a sufficient number of
rounds in a definedperiod of time and reaches a temperature that
couldcook off the round in the chamber. And should the gunmisfire
while in the hot-gun condition, clearing thegun quickly becomes a
very high priority. An inboreexplosion is a catastrophic event and
should beavoided at all cost.
As a member of the hot-gun clearing crew, you willassist the
Gunner's Mates in clearing the misfired roundfrom the gun. They
will actually remove the round from
the chamber and pass it out to a member of the team fordisposal
over the side. While this is occurring, teammembers may be called
upon to set up fire hoses withspecial attachments for internal and
external guncooling. External cooling will normally
beginimmediately after a misfire. Internal cooling can only
bestarted after the propelling charge has been removed.These
procedures are directed by the mount captain.
External cooling directs cooling water to the outsideof the gun
barrel through a standard fire nozzleconfigured to be attached to
the barrel. Internal coolinguses a special applicator, which is
inserted into the gunbarrel, to directly cool the inside of the
Another similar task for magazine crew members isto assist in
the disposal of leaking white phosphorousprojectiles. Both tasks
require regular training andpractice. Since the procedure for the
disposal of leakingwhite phosphorous projectiles is subjected to
regularrevision, this procedure will not be discussed here.
All hands aboard ship should become familiar withcertain
standard gunnery commands. All gun andmagazine crew members,
however, need to becomeespecially familiar with these commands.
Like the guncrew, the magazine crew must operate as a smooth,
NOW MAN ALL GUNNERY STATIONS is thecommand used to direct gun
and magazine crewpersonnel to Lay to assigned stations; get in
battledress; and make preparations to service gun(s) foraction.
Other standard gunnery commands, along with theproper
interpretation, are as follows:
LOADAmmunition handlers in magazine crewsfill projectile hoists
or mechanisms with prescribedammunition.
COMMENCE FIRINGThis is a command fromgunfire control indicating
that firing of designatedgun(s) is authorized.
CHECK FIREA gong or siren is sounded and allguns immediately
RESUME FIRINGGunfire control orders firing tostart again. This
command is given AFTER a CHECKFIRE.
CEASE FIREAll guns stop firing immediatelyupon receipt of this
command. A gong or siren issounded. Gun captains automatically
report to gunfirecontrol on the condition of the gun bore, the
number ofrounds fired and the number of casualties, if any.
Anexample would be Mount 51 bore clear, 10 roundsexpended, no
SILENCEAny member of the gun crew ormagazine crew who observes a
serious casualty ordangerous condition requiring immediate
attention forsafety reasons will sound off SILENCE.
All personnel hearing this command freeze inposition until
further orders or CARRY ON is heard. Thesenior person at the scene
will take charge and remedythe unsafe condition.
In this chapter, we discussed today's naval gunsystems and the
type of ammunition used by each. Thisbasic knowledge should enable
you to perform as anintegral member of a gun or magazine crew. This
manualshould help you in your at-sea experiences and, togetherwith
practical experience gained over a period of time,provide the
necessary guidance you will need to becomea top-notch Seaman. Your
time at sea should be bothchallenging and rewarding.