- AA - Anti-Aircraft.
- AAC - Anti-Aircraft Common.
- AHEAD - Advanced Hit Efficiency And Destruction.
- Amatol - An explosive mixture of ammonium nitrate and TNT.
Ammunition is identified by markings and color-coding on the
items themselves, the containers, and the packing boxes. The
markings and standard nomenclature of each item, together with
the lot number, FSC, NSN, DODIC, and DODAC, completely identify
each item and are used to maintain accountable records. This
appendix gives a basic explanation of markings and color-coding.
Because color-coding is a more ready means of identification, it
is given greater emphasis here.
AP - Armor Piercing. Projectile for use against heavily armored targets.
Very little explosive within the shell, as it must be almost
solid in order to penetrate through armor plate. The USN has
designated all capped armor piercing projectiles as AP
since the early 1900s. See "APC" below.
APC or CAP
- Armor Piercing Capped or (rarely used) Capped Armor Piercing.
Most AP shells have a cap fitted over the nose which is intended
to exert a high initial force on the face of the armor. In
addition, a ballistic cap is usually fitted over the AP Cap to
provide a more streamlined shape for better aerodynamic
characteristics. See "Cap" below.
APDS - Armor Piercing Discarding Sabot.
APFSDS - Armor Piercing Fin-Stabilized Discarding Sabot.
API, AP-I, APT or AP-T
- Armor Piercing Projectiles that include a Tracer (Incendiary).
- A fin-stabilized HE projectile. In German, "Pfeilgeschoss."
- Ammunition in which silk or rayon bags are used to hold the
propellant and the projectile is handled separately. Propellant
bags were manufactured from a special coarse silk known as "shallon"
or "cartridge cloth." This burned without leaving any
smoldering residue in the barrel which would present a safety
hazard when loading the subsequent round. Rayon bags replaced
silk ones in the USN after a serious propellant fire aboard USS
South Dakota BB-57 in 1945 was traced to a spark generated when
a bag was removed from its metallic container.
- Ballistic Cap - Often called a
"windshield," this is a covering on the nose of a projectile
which is intended to provide a more streamlined shape for better
aerodynamic - ballistic - characteristics.
(Back to Top)
- Ballistic Coefficient
- Measure of the ability of a projectile to overcome air
resistance. Ballistic coefficient (BC) = SD / F, where SD is
the sectional density of the projectile and F is a form factor
for the shape of the projectile. Sectional density is
calculated from the mass (M) of the projectile divided by the
square of its diameter. The value of F decreases with as the
pointedness of the projectile increases. A projectile shaped
like a sphere would have the highest F value while one in the
shape of a long needle would have the lowest F value.
- Ballistic Conditions
- Conditions which affect the motion of a projectile in the bore
and through the atmosphere, including muzzle velocity, weight of
projectile, size and shape of projectile, rotation of the earth,
density of the air, elasticity of the air and the wind.
- Ballistic Curve
- Actual path or trajectory of a projectile.
- Ballistic Density
- Computed constant air density that would have the same total
effect on a projectile during its flight as the varying
densities actually encountered.
- Ballistic Efficiency
- Ability of a projectile to overcome the resistance of the
air. Ballistic efficiency depends chiefly on the weight,
diameter and shape of the projectile.
- Ballistic Length or Head
Length - The length
of the projectile's nose. See "crh" below.
- Ballistic Limit
- Velocity at which a given type of projectile will perforate a
given thickness and type of armor plate at a specified
obliquity. Also see "Armor Penetration Definitions," in
- Ballistics, Internal,
Intermediate, External and Terminal
- Internal Ballistics is the study of what the projectile does
from the moment of firing up until it leaves the muzzle of the
weapon. Intermediate Ballistics is the study of the projectile
between the time it exits the muzzle until it overtakes the
muzzle shock waves and enters normal atmosphere. External
Ballistics is the study of what the projectile does as it
travels from the end of the intermediate stage to the target.
Terminal Ballistics is the study of what the projectile does as
it strikes the target.
- The bounding from side to side of a projectile in the bore of
- Base - The after end of the projectile, usually described as that portion
between the driving bands and the bottom of the projectile.
- Base Bleed
- This is a unit on the base of a projectile that generates a
gas, something like a tracer. What this does is fill in the
vacuum that is created behind a rapidly moving projectile and
thus greatly reduces the amount of drag acting on the
projectile. The gas also acts like a long tail, making the
projectile more stable in flight. The end result of these
actions is an increase in range and accuracy.
- Base Cover
- A metal cover that is crimped, caulked or welded to the base
of a projectile. This cover prevents the propellant gasses from
coming in contact with the explosive filler of the projectile
through possible flaws in the metal of the base.
- Base Plug
- A removable seal in the base of a shell which holds in the
- Belt, Ammunition
- Multiple rounds of ammunition that are held together by a
strip of fabric or metal. Used most often for feeding
ammunition to automatic weapons. Ammunition belts may be
disintegrating (linked), non-disintegrating or continuous loop.
- Blind Shell
- A shell containing no explosives or one having its fuzing
disabled so that it does not explode. Often used for proof
tests against armor plate.
- Blind Loaded & Plugged. Same as a Blind Shell.
- Boat Tailing
- Tapering that part of the projectile behind the driving band
to reduce air resistance, especially at low velocities. This
type of design gives a projectile greater range but tends to
increase wear on the gun barrel. It was long thought that boat
tailing caused greater dispersion in the impact pattern, but a
study published in 1978 by the US Army's Ballistic Research Lab
showed that the opposite was true.
- Body - The cylindrical portion of the projectile between the bourrelet and
the driving bands. It is machined to a smaller diameter than
the bourrelet to reduce the projectile surface in contact with
the lands of the bore. The body contains most of the projectile
- Booster - An explosive of special character,
usually of high strength and high detonating velocity, generally
used in small quantities to improve the performance of another
explosive, the latter constituting the major portion of the
charge and made up of a less sensitive explosive. Also see "Gaine."
- Finely machined band or ring of metal just behind the ogive of
a projectile, designed to support the front portion of the
projectile by riding the lands as the projectile travels through
the bore of a gun. Only the bourrelet and the driving bands of
a projectile actually touch the rifling. Some projectiles have
a second bourrelet located between the base of the projectile
and the driving bands. This second bourrelet acts to reduce the
tip-off angle by keeping the projectile body centered in the gun
barrel after the forward bourrelet has exited the muzzle.
- Brisance and Brisant
- Brisance is the measure of how rapidly an explosive develops
its maximum pressure. A brisant explosive is one in which the
maximum pressure is attained so rapidly that the effect is to
shatter any material in contact with it and all surrounding
- Bursting Charge
- The explosive within a shell. Known simply as "Burster."
Some of the more well-known:
Black Powder or Gunpowder
- Used as the burster in most shells prior to the early
years of the twentieth century. A common procedure was
to fill the shell cavity with gunpowder or to put the
explosive into a loosely-restrained bag at the base of
the projectile. In this latter variation, when the
projectile struck the target it was intended that the
bag would be torn loose from its restraints and flung
forward against the interior of the shell. In either
variation, these projectiles relied upon impact shock to
set off the burster. About as reliable as it sounds,
hence the intensive search for better explosives, more
reliable fuzing and the interest in the Zalinsky
"Dynamite Gun" experiments.
- Gun Cotton - See
- Explosive D - USN burster
made from Ammonium Picrate, a salt formed from picric
acid. Adopted prior to World War I, this explosive is
very insensitive to shock, giving it a high margin of
safety. Used for both AP and HC (HE) projectiles.
Lyddite - British Picric
Acid, trinitrophenol. Prior to 1908, the British used
gunpowder as the burster for both AP and Common shells,
but after that date Lyddite came into use for HE
projectiles. In 1909, the Royal Navy began
experimenting with APC using Lyddite as the burster and
began introducing them into service the following year,
even though testing had shown that this filling was more
sensitive to shock than gunpowder and thus prone to
explode prematurely before the shell had a chance to
penetrate almost any thickness of armor plate.
- Melanite - French picric
acid, roughly equivalent to Lyddite.
- Shellite - Adopted just
after the end of World War I, this British burster was a
less sensitive picric acid mixture, containing a mixture
of 70% Lyddite and 30% of the much weaker, insensitive
- Shimose - Japanese picric
acid, roughly equivalent to Lyddite.
- TNA - Japanese tri-nitro-aniso,
designated as Type 91 bakuyaku (Model 1931
Explosive). This was a more stable burster than Shimose.
TNT - Tri-nitro-toulene.
Few, if any, nations used pure TNT. Instead, this was
usually mixed with a desensitizer, such as beeswax. For
example, German shells of World War II used a beeswax
mixture with the concentration of beeswax decreasing
from the head to the base of the cavity.
- Before and during World War I
- Black powder =
0.33 to 0.50
- Guncotton = 0.50
- Picric Acid
(British Lyddite, French Melanite and Japanese
Shimose) = about 1.05 to 1.10
After World War I
German and Italian
TNT = 1.00
British Shellite =
Japanese TNA = 1.05
USA Explosive D =
Other Explosives (torpedo warheads, mines, depth charges)
Amatol (80/20) =
60/40) = 0.82
PETN = 2.21
80/20) = 0.88
RDX = 1.94
Tetryl = 1.39
Torpex = 1.50
German SW types =
Japanese Type 97
(TNT/hexanitrodiphenylamine 60/40) = about 1.07
Two rules of thumb:
1) The effect of the burster may be
taken as being proportional to the square root of the weight of the
2) For the same basic shell design,
the size of the bursting charge is proportional to the cube of the
- Cap - Hardened steel nose piece of an APC projectile. Introduced by Russia
and America in 1894 and adopted by the British Royal Navy in
1903. See illustrations on this page. The cap serves the
1) It is shaped so as to
increase the biting angle; that is, the angle at which the
projectile will penetrate rather than ricocheting.
2) It spreads the shock of
impact over the periphery of the nose instead of allowing the
initial contact to batter the nose tip.
3) It pre-stresses the armor
plate upon impact before the cap shatters away. This means that
the shell body sees a weakened plate.
- Means a ring-like groove or a groove encircling a cylinder.
These have the following uses in ammunition and weapons:
1) On projectiles used in fixed
ammunition: The groove provides a means of securely crimping
the cartridge case to the projectile.
2) On armor-piercing bullets:
The groove is used to lock the jacket of an armor-piercing
bullet to the core.
3) In the rotating band of a
projectile: The groove lessens the resistance from the rifling
as the projectile travels down the gun barrel.
4) Around the base of a
cartridge case: The groove is where the extractor takes hold to
eject the spent case.
5) In the construction of
British large-caliber, wire-wound weapons: Cannelured rings
were used to prevent "steel choke" problems.
- For rifles and pistols, this is usually defined as being the
term for a complete round of ammunition, including the
projectile, cartridge case, propellant and primer. For larger
caliber weapons, especially those using separate ammunition,
this term is usually applied to only the metallic propellant
container. See next definition.
Cartridge Case, Powder
Case, Propellant Case or Casing
- A metallic container for holding powder charges and usually
includes a primer element. This type of propellant container
allows higher rates of fire and is less likely to catch fire in
case of damage from a shell hit. It is also less likely to
suffer a flareback type of disaster caused by the smoldering
remnants from the previous powder charge. However, for larger
caliber guns, it does require more complicated and heavier
handling equipment than does bag ammunition. Germany used a
variation of this for their larger guns, where the propellant
was divided in to two sections, a fore charge in a bag and a
main charge in a cartridge case. Also see "Fixed" and
Cartridge Case Size
- Cartridge cases are usually designated by the diameter of the
projectile they fire and by the overall length of the casing.
Letter suffixes indicate the type of casing. For example, the
famous Oerlikon 20 mm of World War II used 20 x 110RB casings.
This meant that the cartridge cases were for 20 mm projectiles,
had an overall length of 110 mm and had a Rebated Rim. It
should be realized that this is an imprecise method of
identifying casings, as it neglects body diameter and shape.
Most cartridge cases are of one of the following types:
Belted - Cartridge cases
having a belt of metal above the extraction groove
approximately the same diameter as the rim. Denoted by
the suffix B after the diameter and length values.
Rimless - Cartridge cases
having an extraction groove with the base of the
cartridge case being no wider than the rest of the
cartridge case body. This type of cartridge case does
not have a suffix following the diameter and length
Rimmed - Cartridge cases
having a rim at the base wider than the rest of the
cartridge case and not having an extraction groove.
Denoted by the suffix R.
Semi-Rimmed - Cartridge
cases that have a rim that is wider than the body of the
casing with an extraction groove just above the rim.
Denoted by the suffix SR.
Rebated Rim - Cartridge
cases whose bottom rim is smaller in diameter than the
body of the cartridge case. There is an extraction
groove between the rim and the rest of the cartridge
case body. Denoted by the suffix RB.
Cartridge Case, Bottle-Necked
- A cartridge case whose main body diameter is significantly
larger than that of the projectile and has a short "neck"
section which holds the projectile. This design may be used
with any of the above cartridge case types. A bottle-neck
cartridge case holds more propellant for a given length than
will a non-bottle neck cartridge case.
Cartridge Case, Tapered
- A cartridge case whose body diameter increases from the neck
to the rim. This type of cartridge case ejects easier from the
firing chamber than does a "straight" walled cartridge case, as
any backwards motion releases the entire cartridge case body
from the walls of the firing chamber. Most military ammunition
manufactured today has at least some degree of taper.
- Case Ammunition
- Ammunition using a cartridge case to hold the propellant. See
"Fixed" and "Semi-Fixed" below.
- Case Plug or Mouth Plug
- The sealing device in the mouth of a cartridge case used for
separate (semi-fixed) ammunition. This may be of cork, plastic
or cardboard. The USN originally used a brass mouth cup to seal
cartridge cases, but after one "boomeranged" back on board the
transport SS Mongolia and killed two nurses in May 1917,
cardboard ones were substituted.
CCAMS - Course-Corrected Anti-Missile Shell.
Charge or Powder Charge
- The amount of propellant used in firing a weapon.
Common - Common projectiles were originally shells - which literally means a
hollow container - filled with black powder and used for
attacking lightly armored or unarmored vessels. By the 1930s,
this term was used by a few navies to describe any non-armor
piercing shell. By that time, the bursters were less sensitive
explosives, such as TNT. In the USN, Common projectiles of the
1920-1950 period did not have caps or hoods and were designed to
penetrate approximately one-third of their caliber of armor.
See "Special Common" below.
- CLGP - Cannon-Launched, Guided Projectile. Long-range ballistic projectiles
using terminal laser guidance developed during the 1970s for
the USN's 5"/54 Mark 42 and 8"/55 Mark 71 guns.
- CNF - Common, nose fuze. British projectile designation.
- CPBC - Common Pointed Ballistic Cap. British designation for shells of 6"
(15.2 cm) and larger for use against medium thicknesses of
armor. After 1946 this designation was changed to SAPBC -
Semi-Armor Piercing Ballistic Cap.
- CPC - Common Pointed Capped. British designation for shells of 6" (15.2 cm)
and larger for use against lightly armored targets. Little
armor penetration capability but large bursting charge.
- Caliber Radius Head. The pointed head of a projectile is
described in terms of its ballistic length and the radius of
the curvature of its nose. Larger numbers mean a more
streamlined profile. Properly, crh is shown as a dual
number such as 3/4crh, with the first number indicating the
ballistic length and the second number indicating the radius
of the curvature, but it is often abbreviated to a single
number such as 4crh. In the sketch at the right, the dotted
line between Points A and B is the "shoulder" which is the
start point of the nose and the distance between these
points is the caliber of the projectile. In this sketch,
the radius of the curvature is from Point A to Point E and
is four times the caliber of the projectile. The vertical
distance between Points C and D is the ballistic length and
is the most important factor in the design of a shell for
stability in flight. In this sketch, the ballistic length
is 4, as Point E is on the same plane as Points A and B.
From these numbers, this projectile would properly be
described as 4/4crh but this would normally be
abbreviated to just 4crh. Shells of this general
shape are described as being "ogival headed" and have
superior ballistic performance. As can easily be imagined,
a 6crh shell is more pointed and streamlined than is a 4crh
shell. When crh is described as 5/10crh it means
that the radius is 10 calibers long but the ballistic length
is that of a 5crh shell. When a projectile is described as
means that it has a ballistic length of 5 and its nose shape
is conical (infinite radius), not ogival.
Most UN projectiles had
secant ogive ballistic nose shapes which were somewhat more
conical than a simple tangent ogive (smooth merging joint
with cylindrical lower-body side) and gave them a distinct
"shoulder" where the nose met the cylindrical side of the
lower body). This shape has slightly reduced air friction
compared to a tangent ogive nose of the same length above
the cylindrical body. For further information, see the
essay Calculating crh on the Technical Board.
Dark Tracer and Dark
Ignition Tracer -
Tracers that do not ignite until the projectile is 100 to 400
yards (90 to 370 m) from the muzzle. The USN developed these
tracers late during World War II for their 20 mm and 40 mm
automatic weapons. These late igniting tracers eliminated the
blinding effect on gunners at night and made the origin of
tracer fire harder to determine.
DART - Driven Ammunition Reduced Time of flight. Sub-caliber guided
projectile with canard control, intended to improve the
performance of the OTO-Melara 76/62 gun in the antimissile
role. Uses a radio-frequency beam rider guidance system which
utilizes the firing ship's tracking radar.
DBX - Depth Bomb Explosive. USN solid explosive developed during World War
II to replace Torpex and used mainly for depth charges. It is a
mixture of TNT, cyclonite, ammonium nitrate and aluminum.
Factor - The weight of a projectile measured in pounds divided by the cube of
its caliber measured in inches. For example, the USN 16" (40.64
cm) AP Mark 8 weighed 2,700 lbs. (1,224.7 kg). The density
factor of this projectile is thus 2,700 / 163 =
- An explosive device used to set off a larger explosive, such
as a blasting cap used to set off TNT.
- This is usually a rectangular cardboard piece folded into a
triangular shape and placed into the cartridge case between the
wad and the case closure plug or projectile. The distance piece
is used to hold the propellant firmly in place when the amount
of propellant does not completely fill the cartridge case.
Distance pieces are generally used in fixed and semi-fixed
ammunition for 40 mm and larger projectiles.
DPICM - Dual Purpose Improved Conventional Munition. A submunition carried as
payload in projectiles such as the USN 5" (12.7 cm) Cargo
Round. "Dual Purpose" refers to the munition having both
anti-personnel and anti-armor capabilities.
Drag - The effect of air resistance on a projectile. Drag (D) = f(V/A) * K *
Ø * P * Di2 * V2, where f(V/A) is a
coefficient related to the ratio of the velocity of the
projectile to the velocity of sound in the medium through which
it travels. Sound through air at 68°F (20°C) at sea level
travels at 1,128.6 fps (344 mps). K is a constant for the shape
of the projectile. Ø is a constant for yaw (deviation from
linear flight). P is the density of the medium, Di is the
diameter (caliber) of the projectile, and V the velocity. The
degree to which a projectile is slowed by drag is called
retardation (r) given by the formula: r = D / M, where M is the
mass of the projectile. Drag is also influenced by the spin of
the projectile. The faster the spin, the less likely a
projectile will "yaw" or turn sideways and tumble. However, if
the projectile spins too fast, it will not "turn over" at the
top of its trajectory (apogee) and so will not strike the target
- A raised ring of soft metal encircling a projectile. Also
known as "rotating band." These are made of copper, brass or
soft steel. USN driving bands on large caliber projectiles
consisted of 97.5% copper and 2.5% nickel. There may be more
than one band on each projectile. The bands engage the rifling
in the gun barrel, causing the projectile to spin as it travels
through the barrel. They also provide a tight seal so that the
propellant gases do not escape past the projectile as it travels
down the barrel. An "augmented driving band" or "augmented
rotating band" is a slightly thicker strip of metal used when
the rifling in the gun barrel has been worn down. See "Rifling"
- Distance from the geometric center line of a projectile to the
center of gravity of the
ERGM - Extended Range Guided Munition. Effectively missiles fired from a gun
barrel, these special projectiles are currently under
development for the US Navy for the 5"/62 Mark 45 Mod 4 and 155
mm AGS gun systems.
F or FF - Form Factor. A value used for ballistic calculations. See "Ballistic
FAP - Frangible Armor Piercing. FAP is usually a projectile with a tungsten
alloy core which breaks up into multiple fragments when it
strikes a hard surface. The FAP projectile combines armor
penetration, blast effects and incendiary action, all from an
inert projectile that has no more logistical safety problems
than a training round.
FAPDS - Fragmented Armor Piercing Discarding Sabot.
Ammunition - Ammunition in which the cartridge case is attached to the projectile,
similar to a pistol bullet. This type is usually limited to
smaller weapons as the weight becomes prohibitive for
hand-worked guns as the caliber increases past about 4 inches
(10.2 cm). On my datapages for guns firing this type of
ammunition, the value given for "Weight of Complete Round"
refers to the total of the individual weights of the projectile,
cartridge case, propellant and igniter all added together. The
weight of the projectile itself is given separately if
available. Also see "Bag" above and "Semi-fixed/Separate"
(Back to Top)
- A small fin-stabilized projectile. Usually used in large
numbers inside of a single carrier projectile.
Fuze - An overview of fuzes used since the 1900s.
Boresafe Fuze - Type of
fuze having an interrupter in the explosive train that
prevents the fuze from functioning until after the
projectile has cleared the muzzle of the weapon. A "non-boresafe
fuze" does not have this feature.
Base Fuze - Fuze located
at the bottom end or base of the shell. This is the most
common location for AP and SAP projectiles as it avoids
weakening the nose of the shell and protects the fuze from
damage as the projectile passes through armor. Some HE/HC
shells have both nose and base fuzes as this increases the
chances of the shell detonating under differing conditions.
Contact Fuze - A fuze
initiated only after it impacts the target. There are two
general types of contact fuzes, "delay" and "super quick"
both further defined below.
CCF - Course Correcting
Fuze. A smart fuze that uses aerodynamic fins together with
GPS in order to steer an otherwise ordinary ballistic
Delay Fuze - A contact
fuze that detonates the projectile only after it has
impacted and penetrated some distance into the target. A
"short delay" means that the fuze initiates detonation
within a few thousandths (0.00X) of a second after impact.
For naval guns, short delays are generally used for HE/HC
rounds while longer delays are used for AP rounds. Some
delay fuzes have a ring or dial which allows adjustment of
the delay time. For AP projectiles, it is desirable to have
the shell detonate only after it has penetrated past the
armor plating, thus letting it get into the "vitals" of the
target ship's interior. For most AP rounds of the twentieth
century, this delay was usually about 0.030 to 0.070
seconds, roughly equivalent to 35 to 80 feet (10 to 30 m) of
travel. In addition, some thickness of armor plate was
needed to initiate the fuze action. For example, the USN
required that for hits of 0 degrees obliquity that the AP
fuze would not activate unless the armor plate was at least
1 inch (2.54 cm) thick.
Nose Fuze - Fuze is
located at the top point of the shell. This is the most
common location for HC and HE shells as the fuzes can be set
to allow little or no time delay and thus detonate the
bursting charge immediately upon impact. Many nose fuzes
have "auxiliary detonating" fuzes behind them. These
provide a heavier shock which actually detonates the
bursting charge. Auxiliary fuzes also act as a safety
feature by preventing the projectiles from exploding should
the nose fuze be accidentally actuated prior to the arming
of the auxiliary detonating fuze.
Proximity Fuze - Fuze
containing a simple radar that can detect the nearness
(proximity) of a target. Also called "influence fuze."
First used in World War II on USN 5 in (12.7 cm) AA shells
which were called "VT Fuzed" where VT stood for "Variable
Time" (it appears to be a myth that "VT" was a reference to
"Section T," the BuOrd development team for proximity fuzes).
These fuzes are also widely used for anti-personnel rounds
for land artillery as they eliminate the need to accurately
set a time fuze to explode the projectile at a fixed
distance above the target. During World War II, the US Army
called these "posit" or "pozit" fuzes. This term meant that
the proximity fuze allowed the shell to detonate at the most
effective height or "position" above the ground. Since
World War II, fuzes small enough to fit onto 40 mm AA rounds
have been developed. The modern British versions of
proximity fuzes are called TTB - Target Triggered Burst.
Super Quick Fuze or Instantaneous Fuze
- A contact fuze designed to detonate the projectile before
it has penetrated any distance into the target. Super quick
fuzes are commonly used on anti-aircraft rounds that are
designed to shred the outer airframe.
Time Fuze - Fuze has an
adjustable mechanism - usually an incremented dial or "ring"
or, in more modern fuzes, an electronic timer - which is
used to set a delay time. Commonly used for AA projectiles,
smoke and illumination rounds, this type of fuze is used to
set the time between when the shell is fired and when it
1) A machine located on or near
the gun platform that is used to set time fuzes, usually for AA
2) A gun crewman whose job it is
to either operate the Fuze Setter machine or, by using a wrench
or similar tool, to manually set projectile time fuzes.
Fuze Setting in the Hoist
- Hoist fuze setting was first successfully accomplished by the
USN with its 5"/38 (12.7 cm) when coupled with the Mark 37 GFCS.
In this system, the projectiles were inserted nose down into a
cup on an endless chain hoist that led from the handling room
directly below the mount up to the gun breeches. As the
projectile traveled up the hoist, a pawl in the cup, driven by
the GFCS, would engage a lug on the projectile's time fuze
ring. The cup rotated the pawl so as to set the time fuze. The
time fuze setting was automatically and continually adjusted
during the hoist as the firing solution changed. Loaders were
trained to wait until the last possible moment before removing a
projectile and placing it on the loading tray so as to get the
best possible time adjustment.
Fuze Setting at the
Muzzle - Muzzle fuze
setting is normally done by induction. The fuze setter itself
consists of a ring around the muzzle that generates a weak
pulsed-electromagnetic field. As the fuze passes through the
ring, it senses this data signal and sets itself accordingly.
- An explosive container detonated by the fuze and which in turn
detonates the bursting charge.
1) A measure of weight used in
the UK and USA for small propellant charges and for the weight
of small caliber bullets. 1 pound = 7,000 grains. 1 gram =
2) An individual particle of
propellant. A degressive or regressive grain is one whose total
burning surface area decreases as it burns. Propellant grains
formed in balls, cords, pellets and thin sheets burn
degressively. Degressive grains are generally used in weapons
having a short barrel length. A neutral burning grain is one
whose total burning surface remains approximately constant as it
burns. Single perforated grains and star perforations are
examples of neutral burning grains. Technically, grains formed
in thick sheets or strips burn degressively, but the change in
burning area is so small that they may be considered to be
neutral burning. A progressive grain is one whose total burning
surface increases since it burns from both the inside and the
outside at the same time. Grains with multiple perforations and
those in rosette shapes burn progressively.
- Improved British AP projectile developed late in World War I.
The ballistic cap for these projectiles was painted green to
distinguish them from older models, hence the nickname.
Following the failure of British AP projectiles to detonate
properly during the 1915 Battle of Jutland (Skagerrak), the
Royal Navy began an intensive effort to produce better
versions. These were introduced into service starting in 1918
and had a new delay-action base fuze patterned after the ones
used on German 28 cm Psgr. APC projectiles. Greenboys had
better armor penetration abilities compared to the older models,
thanks to an improved body and the new "Hadfield" hardened AP
Grommet - Projectile cover used to protect the rotating band of projectiles
during handling. The grommet is removed before the projectile
HC - High Capacity. A USN designation for projectiles intended for use
against lightly armored targets. Contains a relatively large
amount of explosive as compared to an armor piercing or common
projectile. Burster was between 7.0% to 12.6% of total
- HE - High Explosive or High Effect. Same as HC.
- Head Length
- The length of the projectile's nose. Same as "Ballistic
Length." See "crh" above.
- HEI or HE-I
- HE projectiles that include an Incendiary.
- HE-I-SD - Self-destructing incendiary HE projectile.
- HE-CVT - HE with a Controlled Variable Time (proximity) fuze.
- HE-IR - HE with an infrared fuze. These rounds use a passive IR fuze that
operates only on the infrared spectrum detected in the exhaust
gasses of jet and hot missile targets. These fuzes are harder
to jam than radar-type proximity fuzes.
- HE-MOM - HE Multirole OTO Munitions. OTO-Melara ammunition with proximity
fuzing and tungsten cubes surrounding the bursting charge.
- HE Pre-Fragmented OTO Munition.
- HE-PD - HE with a Point Detonating (contact) fuze.
- HE/SD - Self-destructing HE projectile.
- HET or HE-T
- HE shell with a tracer.
- HE-T/SD - Self-destructing HE-T shell.
- HETF - British high explosive projectile with time fuze.
- HE-VT - High Explosive with a Variable Time (proximity) fuze.
HMX - Cyclotetramethyenetetranitramine. A white crystalline powder used as
a high energy oxidizer in propellants and explosives.
Hood - Thin cap used on USN Special Common projectiles to attach the
windshield to the projectile body.
- Literally means "water seeking" and is used to describe a
material that readily absorbs water (usually from the
Igniter or Igniter Patch
- Bag ammunition charges have a small patch at one or both ends
containing black powder (gunpowder). This is used to set off
the main propellant charge. See "primer" below.
ILLUM or Illuminating
- Commonly called "Star Shells," these projectiles are usually
filled with magnesium and are used at night to light up
(illuminate) the target. Many use a parachute in order to slow
(Back to Top)
- Illumination round with a Mechanical Time fuze.
- K Shells
- British term for projectiles using dye bags. See "Splash
- A piece of lead foil is sometimes inserted at the top of the
propellant in a cartridge case. The lead foil aids in scouring
away residue left from the driving bands or unburnt propellant.
- Threaded eyebolt which fits into the fuze cavity (nose or
base), permitting heavy shells to be handled by means of a
Link - The part of an ammunition belt which joins the individual rounds
together. Usually, one link holds one round. "Disintegrating
Link" means that the links holding each individual round to the
next round separate from each other and from the cartridge as
each round is fired.
LRBA - Long Range Bombardment Ammunition. USN munition developed as part of
the "Gunfighter" program of the late 1960s. These were unguided
5" (12.7 cm) projectiles enclosed in a sabot and fired from 8"
(20.3 cm) gun barrels. These sub-caliber projectiles had a
maximum range of about 72,000 yards (66,000 m) and were
successfully used against Viet Cong targets at 70,000 yards
LRLAP - Long Range Land Attack Projectiles. These are being developed as part
Meplat - The flat or blunt area at the tip of a projectile. Usually specified
by its diameter.
MPDS - Missile Piercing Discarding Sabot.
MT - Mechanical Time. Designation for Time Fuzes used by the US Navy. See
"Ring or Time Fuze" below.
NACO - Navy Cool. A cooler-burning propellant currently in use by the US
NCT - Nitrocellulose Tubular.
- A short-fibered cotton bleached and purified to the point
where it is 90% pure cellulose. This material forms the basis
for nitrocellulose used in propellants. See "Propellants"
- The Lifting Plug (see above) used for nose-fuzed projectiles.
- The aerodynamic, gyroscopic and inertial forces acting on a
spinning projectile are in constant flux as it travels through
the air. As the various forces readjust themselves, the nose of
the projectile describes a small arc around the axis of travel.
This motion is called "nutation" from the Greek word for
"nodding," which is a good description of what the projectile
- In projectiles, this is a band, usually made of nylon, below
the driving bands. The band helps prevent propellant gasses
from escaping past the projectile as it travels up the gun
barrel. Commonly described as the "Forward Obturator" or
"Forward Located Slip Obturator" to distinguish it from the
- The curved area making up the nose of a projectile. Usually
defined as extending rearwards from the tip of the projectile's
nose to the main cylindrical portion or bearing surface. From
an ordnance manual: "Often a convex solid of revolution
generated by an arc of a circle whose center lies on the side of
the axis of revolution opposite to the arc." Whew, glad I found
that out! In layman's terms, the head of the projectile is
usually bullet-shaped. See "crh" above.
(Back to Top)
- Reactive compound which gains electrons during an
oxidation-reduction chemical reaction. In propellants, this is
the ingredient that provides oxygen for the burning process.
- Iron armor piercing shells of the mid to late 19th century
which were hardened by casting the projectiles point downwards
and forming the heads in an iron mold. This process rapidly
chilled the hot metal of the nose and made it intensely hard.
The remainder of the projectile mold was formed of sand,
allowing the metal of the shell body to cool more slowly, making
it tough but not brittle. These shells were powder-filled, but
did not use a fuze. Instead, they relied upon the shock of
striking the target to set off the burster. These shells were
effective against wrought iron armor, but shattered against
steel armor. Named after the inventor, Sir William Palliser.
PBX - Plastic Bonded Explosive. A mixture of cyclonite, HMX, PETN and a
plastic binder. Has high mechanical strength, excellent
chemical stability and is shock resistant.
PETN - Pentaerythritol tetranitrate. Shock-sensitive material used in
explosives, blasting caps and in some mono-propellants.
- PFHE - Proximity Fuzed High Explosive.
- Posit or Pozit Fuze
- See "Fuzes" above.
- Powder Bags
- See Bag Ammunition, above.
- An individual unit of propellant. Commonly used in the form
of strips, cords (strings), hollow tubes (single perforation) or
multi-perforated cylinders. Cord grains have steadily
decreasing burning surfaces. Single perforated grains and
strips have a practically constant burning surface.
Multi-perforated cylindrical grains have an increasing burning
surface, since combustion proceeds from the outer diameter
inward and from the perforations outward. A propellant grain
with a decreasing burning surface will tend to generate less
propellant gas as it burns while a propellant grain with an
increasing burning surface will tend to generate more propellant
gas as it burns.
- A projectile, usually AA or anti-personel, that has been
sectioned so as to break up into uniformly-sized pieces when the
Primer - A device used to provide a flame for the purpose of setting fire to a
propellant charge. Also called an "igniter." Primers are
divided into two types, depending upon the type of ammunition
used by the gun: 1) Case and 2) Lock. Case primers, as their
name implies, are used for guns firing case ammunition. These
are small containers of an explosive such as mercury fulminate
that are installed into the base of the cartridge case. Lock
primers are used for bag guns and are inserted by hand into the
firing lock of the gun. Primers are also divided into three
classes, depending upon the method of firing: 1) Percussion, 2)
Electric and 3) Combination. Percussion primers are fired by
the mechanical impact of a firing pin. Electric primers are
fired by passing a current through a resistance element
surrounded by an initiating mixture. Combination primers may be
fired by either of these methods, which allows for a mechanical
backup if the electrical supply system to the gun fails.
- In 1860 General Thomas Jackson Rodman of the United States
Army, realizing the advantages to be gained by increasing the
propellant burn time, proposed the use of large grains of very
dense black powder for this purpose. As a result of his
research, he also proposed that perforated grains be used in
order that the burning surface of each grain might be increased
as combustion proceeded. The use of these grains gave a means
of better regulating the ballistic action of black powders, and
thus reduced undesirable items such as fluctuations in muzzle
velocity. Different grain forms were tried, such as
spherohexagonal and various prismatic shapes, including the
hexagonal prism with a single perforation. The latter form was
widely used in larger guns. The use of such grains was the
first notable advance in securing a powder which would burn
progressively, that is, with increasing evolution of gases and
- An overview of some of the more common propellants used by
naval guns since the 1880s.
Single-Base, Double-Base and Composite Base Propellants
- Propellants are classified into three types;
single-base, double-base and composite. Single base
propellants are primarilly gelatinized nitrocellulose
that do not contain an explosive ingredient such as
nitroglycerin. Double-base propellants are mainly
compositions that are predominately nitrocellulose and
nitroglycerin. Composite propellants are compositions
that contain mixtures of fuel and inorganic oxidants but
do not contain a significant amount of nitrocellulose or
nitroglycerin. There are also combinations of composite
and double-base propellants.
Ballistite - This is a
double-base propellant for rockets. It is composed of
nitrocellulose and nitroglycerin, blended together with
diphenylamine, which acts as a stabilizer. This mixture
burns with a considerable amount of flash and smoke, and
generates a great volume of gas. Ballistite burns
progressively, but at a rate dependent upon the
composition and physical characteristics of the
propellant grain, the temperature of the propellant
prior to ignition and the gas pressure obtained during
Black Powder - Commonly
known as "gunpowder," this was obsolete by the 1880s and
rarely used after 1900 by the major powers as a
propellant. It did continue to be used for igniter
patches on bag ammunition. Black powder is a mixture of
potassium nitrate or sodium nitrate, charcoal and
sulfur. It is hydroscopic and subject to rapid
deterioration when exposed to moisture. It is also one
of the most dangerous explosives to handle because of
the ease with which it is ignited by heat, friction or
spark. Black powder as a gun propellant has several
disadvantages: (1) it leaves a large amount of residue,
(2) it produces large quantities of smoke, (3) it causes
rapid erosion of the gun bore and (4) its velocity of
reaction is too rapid, giving an abrupt hammer blow to
the projectile and then rapidly decreasing energy. This
last reason is why gunpowder guns had short barrel
lengths. Muzzle velocity was generally less than 1,600
fps (488 mps).
Brown Powder or Cocoa Powder or Slow Burning Cocoa (SBC)
- Propellant developed in the late 19th century. An
underburned straw charcoal was used in this powder and
gave it the characteristic color from which it took its
name. This charcoal gave a denser and hence slower
burning structure to the powder and thus permitted
better regulation of pressure. Brown powder is similar
to black powder (gunpowder), each being a mixture of
potassium nitrate, charcoal and sulfur, but brown powder
has a lower sulfur content (3% versus 12%) and a
correspondingly higher potassium nitrate content. The
reduced sulfur content results in a slower rate of
deflagration (burning) and the higher potassium nitrate
content supports a more complete burning of the charcoal
and thus releases more energy. The slower burning
nature of brown powder allowed longer barrel lengths and
thus higher muzzle velocities, with the maximum being
about 2,200 fps (671 mps). However, this propellant is
notorious for producing vast quantities of smoke.
Cordite - A smokeless
powder composed of nitroglycerin, guncotton and a
petroleum substance, usually gelatinized by the addition
of acetone, and the mixture then pressed into cords
which resemble brown twine. Widely used by the British
with Mark I being the first version adopted by
the Royal Navy in 1889. This propellant was much more
powerful and thermally efficient than gunpowder or brown
powder, as shown by tests with early British 6 inch
(15.2 cm) QF guns. These replaced their 55 lbs. (25 kg)
charge of brown prismatic powder with only 13 lbs. (6
kg) of Mark I propellant. Mark I cordite did burn very
hotly and was found to be detrimental to gun barrels
life, as the high temperatures caused rapid wear. For
this reason, the proportions of nitroglycerine and
nitrocellulose were revised in order to increase the
barrel life. This new propellant was designated MD
(for Modified) and came into service in 1901. MD
charges were about 25% heavier than Mark I for the same
ballistic result but doubled the life of the guns. Both
Mark I and MD were in use during World War I, and both
had poor storage characteristics with their stability
degrading over time. The double-based nature of these
propellants, containing a substantial amount of
nitroglycerine in their composition, was significantly
more susceptible to ignition than their single-base
American counterparts. These unfortunate traits led to
several ships suffering magazine explosions both in
action and in harbor. A study performed after World War
I found that MD tended to form highly unstable
micro-sized dust particles consisting of nitrocellulose
and iron pyrites. In 1927, after a study of the German
RP C/12 solventless propellant (see below) used
during World War I, British chemists developed a more
stable version called SC (solventless cordite,
also known as solventless carbamite). This was used to
replace older propellants as rapidly as possible. SC
was used extensively during World War II and had a
better safety record, although the loss of HMS Hood may
be partially attributed to it. Due to the presence of
calcium in the small amount of chalk used to counteract
traces of residual acids, SC had a very bright "flash,"
a characteristic which led to the development of
flashless propellants (see below). British cordite
propellants were designated by the type and the cordage
diameter size, which for MD cordite was in 0.010 inch
(0.254 mm) increments and for SC cordite was in 0.001
inch (0.0254 mm) increments. For example, MD45
meant MD-type cordite in 0.450 inch (11.4 mm) diameter
cords while SC350 meant SC-type cordite in 0.350
inch (8.89 mm) diameter cords. Some cordite in tubular
form was manufactured, designated as SC T
followed by two sets of numbers, with the first number
indicating the external diameter and the second number
indicating the internal diameter, with both numbers in
0.001 inch (0.0254 mm) increments. Cordite in various
forms was also used by the Japanese from about 1890 to
the end of World War II. Different formulations were
used, most containing about 30 percent nitroglycerin and
65 percent nitrocellulose with the remainder being
stabilizers. The nominal diameter of the Japanese cords
was given in units of 0.1 mm (0.004"). For example, the
Japanese propellant DC80 was cordite with cords
of 8 mm (0.315") diameter. Cordite N is used as
a propellant in aircraft gun ammunition. It actually
contains three main explosive components, nitroguanidine,
nitrocellulose, and nitroglycerin. Cordite N is very
cool burning and produces little smoke and almost no
Flashless Powder -
Propellant formulation that reduces the amount of flame
emitted from the gun muzzle. Useful in night
engagements as it does not give away the position of the
firing ship. Not really "flashless" but much less so
than standard propellants. British flashless
propellants in use during World War II were produced in
primarily in slotted tubular form and were of the form
NF/S 164-048 with the first number indicating the
external diameter and the second the internal diameter,
both in 0.001 inch (0.0254 mm) increments. However,
with guns larger than 5.25" (13.3 cm), full flashless
charges became too bulky for existing turret
arrangements and so only the 6" (15.2 cm) Mark XXIII had
been issued such charges and they were "reduced flash"
or "non-blinding" rather than flashless.
Gun Cotton - Explosive
substance formed by the nitration of cotton or some
other form of cellulose. As a projectile force, gun
cotton has around six times the gas generation of an
equal volume of black powder and produces less smoke and
less barrel heating. Guncotton releases about 1,100
kilocalories (Kcal) of energy per kilogram, nearly twice
that of black powder, almost the same as TNT and
two-thirds that of nitroglycerine. Moist or "wet"
guncotton is relatively stable but can be easily
exploded by using a small amount of dry guncotton (which
is sensitive to shock) to start the deflagration. Some
history about guncotton: In 1838 the French chemist
Theophile Jule Pelouze discovered that an explosive
could be produced by nitrating cotton, that is, by
treating cotton with nitric acid in such a way as to
cause NO2 groups from the nitric acid, HNO3,
to enter into combination with the cotton cellulose. He
thus produced cellulose nitrates, generally called
nitrocellulose. His explosive was the first guncotton,
but it was an inconsistent mixture and was not put to
practical use. The German-Swiss chemist Christian
Friedrich Schönbein discovered in 1845-46 that by
nitrating cotton with a mixture of nitric and sulfuric
acids, an explosive of good quality would result and
that the nitration process could be satisfactorily
controlled. Manufacture of guncotton via his process
was undertaken in several European countries, but poor
quality control led to a series of disastrous explosions
in many of the factories where it was being produced.
The researches of various investigators during the
middle of 19th century, notably of General von Lenk in
Austria and the British chemist Frederick Abel at
Woolwich Arsenal (who, with James Dewar, later invented
cordite), showed that the danger was due to the presence
of impurities, which could be removed by careful courses
of treatment. The methods of purification which they
introduced consisted principally in washing and boiling,
together with pulping the material to facilitate
cleansing. In 1865, Abel was the first to safely
produce good quality guncotton.
Nitrocellulose - See Gun
Cotton, above. Used as the base of most USN
propellants. During World War II, the primary USN
propellant was a single-base, multi-tube form made up of
99.5% NC (12.6% N), 0.5% diphenylamine. The USN used a
flat, short cylindrical grain design that usually had
seven perforations with the websize varying from 0.023
in (0.58 mm) for the short 3 in (7.62 cm) gun to about
0.174 in (4.42 mm) for the 16 in (40.64 cm) guns. The
USN's propellants had a good safety record partly due to
the harder-to-ignite and slow burning nature of their
nitrocellulose propellants and partly due to the quality
of their manufacturing process. The French also used
nitrocellulose, but in a strip form. These French
propellants were designated with BM followed by a
number which indicated thickness, such as BM15.
This number was somewhat arbitrary, but a larger number
did indicate a thicker strip. Early French
nitrocellulose was susceptible to spontaneous ignition,
but this was improved by the addition of diphenylamine
as a stabilizer.
RP - Rohr-Pulver. "Tube
powder," the descriptive designation given to German gun
propellants. German propellants were manufactured in
the form of hollow tubes. The propellants were
classified by model year and by the external and
internal diameters of the tubes in millimeters. For
example, RP C/38 (14/4.9) meant a tube powder
first introduced in 1938 that had an external diameter
of 14 mm (0.551 in) and an internal diameter of 4.9 mm
(0.193 in). There were several compositions used from
1912 to 1945. Earlier ones used nitroglycerin while
later ones used diethylene glycol dinitrate, which was
cooler-burning and less bore erosive. All were
resistant to exploding even when exposed to a hot fire.
For instance, when the small battleship Gneisenau was
bombed at Kiel in 1942, over 23 tons (24 mt) of
propellant was ignited in a forward magazine. There was
no explosion even though turret "Anton" was lifted at
least 50 cm (20 inches) from its mounting by the gas
pressure generated by the deflagration. As noted above,
the British did extensive studies of RP C/12 after World
War I and developed "solventless cordite" (SC) based
upon the results.
SD - French "solventless"
propellant produced during the 1930s for 380 mm, 330 mm
and a few other guns. Like British SC, French SD
appears to have been developed from a study of German
RPC/12, as it was in a single tube grain and the
composition was similar in its proportions of
nitrocellulose, nitroglycerin and centralite. SD19
was designed for the 330 mm guns while SD21
was used for the 380 mm guns.
Smokeless powder - Refers
to modern gunpowder, which is really not "powder" but
rather flakes of nitrocellulose and other substances.
Not really "smokeless" but much less so than black
powder or brown powder.
USN Smokeless Propellants
- In the USN smokeless powder is designated as SP
and is usually a uniform ether-alcohol colloid of
purified nitrocellulose with a quantity of diphenylamine
(D suffix) or carbamite (ethyl centrality) (C
suffix) added for stability. Smokeless powder is
generally unstable as it contains NC and two volatile
substances, ether and alcohol. Its length of usefulness
depends largely on the conditions under which it is
stowed. Moisture or heat speeds its deterioration and
the combination of the two is extremely damaging to the
propellant. SPDF is a flashless formulation of
SPD. SPDX is a water-dried SPD. SPDW is
reworked propellant intended for target use. SPDN
is a diphenylamine-stabilized smokeless powder to which
nonvolatile materials have been added to reduce its
hydroscopic tendencies. The N stands for
nonhygroscopic. SPCG is a flashless double-based
propellant containing nitroglycerine and stabilized with
- Non-explosive projectile used for training spotters. These
produce a dense cloud of smoke approximately the size of those
produced by high-explosive projectiles.
RAP - Rocket-Assisted Projectile.
Rim - The lip or flange around the case head on a cartridge case which
provides purchase for the extractor claw.
- See "Time Fuze" above.
- See "Driving Band" above.
Sabot - Pronounced "sa-BO." Literally means "hoof" in French. This is a
lightweight carrier into which a projectile smaller than the
barrel diameter (usually called a sub-caliber round) is
centered. The carrier fills the bore of the weapon from which
the projectile is fired and is normally discarded a short
distance from the muzzle. There are two common uses for this
type of ammunition. The first use is when the projectile is made
from a very heavy, dense material, such as in tungsten
penetrators. Making the projectile smaller than the barrel
diameter keeps the shell weight about the same as that of a
conventional projectile and thus does not overstress the gun
barrel. The second use is to give a light-weight projectile a
higher muzzle velocity. This means that the same amount of
propellant will throw the smaller projectile a longer distance
than it will the conventional projectile.
- Japanese for "fragmentation." Also known as "incendiary
shrapnel shells" (shôi ryûsandan). These were AA rounds which
contained hundreds of incendiary-filled steel tubes and
officially designated as "Type 3 Common Shells" (3 Shiki
tsûjôdan). The incendiary filling was "Elektron" metal (45%),
barium nitrate (40%) and rubber (14.3%) together with sulfur
(0.5%) and stearic acid (0.2%). "Elektron" was a trade name for
a metal alloy composed primarily of magnesium (90%) with the
balance being aluminum (3%), copper (3%), zinc (2%) and silicon
(2%). Besides their incendiary effect, the steel tubes also
acted as shrapnel. The Type 3 was first deployed in 1942 for 20
cm (8 in) and larger guns and in 1943 for the 12.7 cm/40 (5 in)
AA and 12.7 cm/50 (5 in) DP guns. The 46 cm (18.1 in) Type 3
projectiles for the Yamato class battleships may have been
nicknamed "The Beehive" but this could be apocryphal. A time
fuze was used to set the desired bursting distance, usually
about 1,000 meters (1,100 yards) after leaving the muzzle.
These projectiles were designed to burst in a 20 degree cone
extending towards the oncoming aircraft with the projectile
shell itself being destroyed by a bursting charge to increase
the quantity of steel splinters. The incendiary tubes ignited
about half a second later and burned for five seconds at 3,000
degrees C, producing a flame about 5 meters (16 feet) long.
These shells were thought to have a larger lethal radius than
did standard HE AA rounds. The concept behind these shells was
that the ship would put up a barrage pattern through which an
attacking aircraft would have to fly. However, the USN pilots
considered them to be little more than fireworks and not an
effective AA weapon.
SAP - Semi-Armor Piercing. Projectiles supplied for smaller guns for use
against moderately armored targets.
SAPBC - Semi-Armor Piercing Ballistic Cap. British projectile designation.
See "CPBC" above.
SAPER - Semi-Armor Piercing Extended Range.
- Semi-Armor Piercing High Explosive Incendiary Tracer.
SAPOM - Semi-Armor Piercing OTO Munition.
- Semi-Armor Piercing OTO Munition Extended Range.
SD - Sectional Density. A value used for ballistic calculations. See
"Ballistic Coefficient" above.
Separate Ammunition -
Semi-fixed ammunition is when the projectile and cartridge case
are separate pieces but are joined together prior to firing.
This term has become interchangeable with separate ammunition,
which is where the projectile does not attach to the cartridge
case but they are both rammed together into the breech. These
types of ammunition were commonly used for AAA and DP type
weapons used in World War II as this allowed each piece to be
light enough to be manually handled. For example, the US 5"/38
(12.7 cm) Mark 12 used a projectile with a separate brass
cartridge case which held the propellant. These were laid
together in the gun's loading tray after which a rammer pushed
them "home" into the breech which then closed automatically.
Technically, the 5"/38 (12.7 cm) used separate ammunition, but
most descriptions of this weapon including USN official ones use
the term semi-fixed. Separate ammunition is used today on many
weapons including both USA and Italian 5"/54 (12.7 cm) guns.
- The shock on a projectile when fired from a gun or when it
strikes a target. Used to enable many fuze mechanisms such as
impact and time fuzes.
- A type of coarse silk used in making propellant bags. Also
known as "cartridge cloth."
Shark - A British ASW projectile developed near the end of World War II.
Weighed about 96 lbs. (43.5 kg) and could be fired from any 4
inch (10.2 cm) gun. Not known if successful in battle, but
trial results were considered to be very encouraging.
- This is sometimes designated as being in "calibers," similar
to barrel length. For instance, if a 16 inch (40.64 cm) shell
is listed as being 4 calibers long, then this means that it is
about 16 x 4 = 64 inches (1.626 m) long from nose to base.
Short Delay Fuze
- See "Contact Fuze" above.
Shot - An archaic term for a solid projectile intended for penetrating
armor. Mostly replaced by AP after about 1900.
- Also known as "spherical case," this was a type of
anti-personnel ammunition which consisted of a shell containing
metal balls in the front and a small bursting charge at the rear
which was detonated by a time fuze set to explode just before
reaching the target. This was first adopted by the British Army
in 1803 and is named after the inventor, Lt. (later General)
Henry Scrapnel (sometimes spelled as "Shrapnel") of the British
Army. This term has been used in the past to define shell
fragments from most kinds of bursting projectiles, not
necessarily anti-personnel types. Currently, the more accurate
term "shell splinter" is in general use.
Smoke or WP
- Projectiles used to create a small smoke screen. Usually
filled with white phosphorous (WP or "Willey Pete").
SP - Small Pebble. Large grain, densely packed gunpowder. The powder was
tightly pressed into a block and then broken into small pieces
or "pebbles." See "Prismatic Powder" above.
- USN unofficial designation of the 1920-1950 period for those
Common projectiles that used both windshields and hoods. These
projectiles were designed be penetrate approximately one-third
to one-half their caliber of armor. They differed from AP
projectiles by not having a cap and having a larger burster
cavity. Burster was 2.1% to 3.99% of total shell weight.
Spin - A standard, fin-less projectile must be spun in order to maintain
stability in flight. Under or over spun projectiles will tend
to tumble in flight or not turn over at apogee and thus do not
achieve good range or penetration performance. Generally
speaking, the larger the diameter or longer the projectile, the
slower it can be spun, in terms of rotations per second (RPS),
in order to maintain stability.
- In group actions, when more than one ship is firing on the
same target, it is difficult to determine which shell splashes
are from which ship. This is important to know in order for
each ship to be able to adjust its fire onto the target. The
solution was "Splash Colors," first used by the USN during Force
Battle Practice in 1930 and in use by most navies during World
War II. The void space between the armor piercing cap and the
windshield for AP projectiles was filled with a colored dye by
the shell manufacturer. The dye is seen when the shell impacts
in the sea and colors the resulting splash - hence the name. By
using different colors, each ship could distinguish between
their shells and those fired by other warships. In the USN, the
dye was a dry powder which was packaged in paper bags.
Interestingly, the USN used this dye to compensate for minor
weight variations that crept in during the projectile
manufacturing process. For example, the 16 inch (40.64 cm) Mark
8 AP had a nominal 1.5 lbs. (0.68 kg) dye bag, but this was
allowed to be as large as 3.0 lbs. (1.36 kg) in order to bring
underweight projectiles up to the standard weight of 2,700 lbs.
(1,225 kg). Usually, a particular color was assigned to each
ship. For example, the colors used by the USS Iowa (BB-61)
class battleships were as follows:
USS Iowa - Orange
USS New Jersey - Blue
USS Missouri - Red
USS Wisconsin - Green
- Fragments of a shell after detonation.
Squib - A firing device that burns with a flash and is used for igniting black
powder or pellet powder.
- See "Illum" above.
Super Quick Fuze
- See "Contact Fuze" above.
- See "Fuzes" above.
TP-T - Target/Practice projectile with Tracer.
TTB - Target Triggered Burst. See "Proximity Fuze" above.
VD - Variable Delay. USN terminology for base fuzes designed for
armor-piercing projectiles. Complete designation was "VDXF"
where "X" was the Mark number and "F" stood for fuze. See "Fuzes"
VT - Variable Time. See "Fuzes" above.
Wad - For cartridge cases using a loose powder propellant which does not
fill the cartridge, a cardboard disc is placed on top of the
powder and held with a distance piece to keep the propellant
firmly in place.
Window - Projectiles containing metal foil strips, which, when scattered high
in the air by the small burster charge, serve to jam radar sets
by creating a multitude of images.
- See "Ballistic Cap" above.
World War I Projectile
Weight - Typical
World War I AP caps weighed about 5% of the total projectile
weight. World War I windscreens, when used, were tiny, only
about 0.5-2% of the projectile weight. The need for increased
range caused more World War II-like long windscreens to be added
to some projectiles by the end of World War I. Burster weight
was about 2.5-4% for APC, 4-6% for Common, 6-11% for HE and
about 8-10% for CPC.
World War II Projectile
Weight - Windscreens
weighed 3-5% (depending on length) for most World War II
projectiles, though German post-1930 L/4,4 and L/4,6 AP
projectiles used brittle aluminum windscreens that only weighed
about 1% of the total projectile weight. Hoods weighed about
5%. AP caps had more variable weights, with 8-14% being the
usual range for large projectiles. Smaller projectiles,
especially U.S. Navy 6 inch (15.2 cm) and 8 in (20.3 cm) AP
projectiles, had much heavier caps. The U.S. Navy 335 lbs. (152
kg) 8 inch (20.3 cm) Mark 21 AP projectile had about a 17% cap
weight, while the 130 lbs. (59 kg) 6 inch (15.2 cm) Mark 35 AP
projectile had a 19-22% cap weight - both of these projectiles
had the bluntest, most-hemispherical nose shapes of all
projectiles in use. Explosives made up about 2-5% for APC,
although the USN used about 1.5% in their "super-heavy"
projectiles. HE or HC projectiles had about 6-8% explosive.
Some exact breakdowns:
inch (40.64 cm) 2,700 lbs. (1,225 kg) AP Mark 8 Mod 6 (Data from
NPG Report 3-47)
AP cap: 312 lbs. (141.5
Windscreen: 32.4 lbs.
(14.7 kg) [1.2%]
Bursting charge: 40.5
lbs. (18.4 kg) [1.5%]
Body weight (including
bursting charge): 2,355.6 lbs. (1,068.5 kg) [87.2%]
40.64 cm (16 inch) 2,271 lbs. (1,030 kg) Psgr. L/4,4 (mhb) (Data
from NPG Report 101)
AP cap: 363 lbs. (164.7
Windscreen: 27 lbs.
(12.3 kg) [1.2%]
Bursting charge: About
53.4 lbs. (24.2 kg) [2.3%]
Body weight (including
bursting charge): 1,880 lbs. (852.8 kg) [82.8%]
(Back to Top)
USN Projectile Markings of the World
War II era for projectiles larger than 40 mm
Click on this picture for a larger
Bag charges were lettered in
0.375 inch (1 cm) black characters on the side of the bag
opposite the lacings, with the bottom of the letters towards the
ignition end of the bag. Markings were as follows:
Ammunition Lot Number
Caliber and length of gun in calibers
Type of charge (full, reduced, service, target, high-capacity,
Index Number of the powder charge
Number of sections per charge
Initial Velocity and weight of projectile with which charge can be
(when two different weight projectiles are used) Initial Velocity
and weight of other projectile
The word "FLASHLESS" in 0.375 inch (1 cm) yellow characters if the
charge is either a flashless type or is propellant to which
flashless pellets have been added
In addition, cases with flashless
propellant had the word "FLASHLESS" painted on the side of the case
and a 0.75 inch (2 cm) "F" painted in yellow on the case head
stands for Naval Gun Factory, which was located at the Washington
D.C. Navy Yard
Ammunition is identified
by markings and color-coding on the items themselves, the
containers, and the packing boxes. The markings and standard
nomenclature of each item, together with the lot number, FSC, NSN,
DODIC, and DODAC, completely identify each item and are used to
maintain accountable records. This appendix gives a basic
explanation of markings and color-coding. Because color-coding is a
more ready means of identification, it is given greater emphasis
F-1. Markings stenciled or stamped on munitions items
include all information needed for complete identification.
Components in which all explosive, incendiary, or toxic
materials have been simulated by substitution of inert material
are identified by impressed INERT markings. Components in which
all explosive, incendiary, or toxic materials have been omitted
are identified by stamped EMPTY markings.
- AMMUNITION LOT
F-2. Each item of ammunition is assigned a complete round
or item lot number when it is manufactured or is at the LAP
plant. See MIL-STD 1168-A for a description of the current
system. See MIL-STD 1168 for a discussion of the old lot
numbering system. Figure F-1 breaks down a typical ammunition
lot number showing both the new and old systems.
Figure F-1. Typical Lot Number System
AMMUNITION FEDERAL SUPPLY CLASSES
F-3. Conventional ammunition is FSG 13. Within this group,
ammunition is further broken down by two more numbers that
identify the general type or family in which the item falls.
Table F-1 lists the FSCs.
Table F-1. FSC Group 13 Classes
AMMUNITION NATIONAL STOCK NUMBERING SYSTEM
F-4. Each complete round or item of conventional ammunition or
associated explosive component is identified by its own NSN. The
first four numbers of the NSN is the FSC. It is followed by the
National Item Identification Number, or NIIN, which consists of
a two-number code identifying the country of manufacture and a
seven-number item identification. See Figure F-2 below.
Figure F-2. Example of an NSN
DEFENSE IDENTIFICATION CODE
F-5. A DODIC is a single letter and three numbers or, in the
case of small guided missiles, two letters and two numbers. It
is attached at the end of all NSNs to denote interchangeability
of the item. Communications between ammunition units often use
an ammunition item DODIC. See Figure F-3 for a conventional NSN
with DODIC added, demonstrating interchangeability between
various model numbers and the designators of an ammunition item
Figure F-3. Sample DODIC
DEPARTMENT OF DEFENSE
F-6. The DODAC includes the FSC of the ammunition and the DODIC.
The code is used on all using unit DD Form 581s, DA Form
3151-Rs, and most ammunition reports. The DODAC is used instead
of the DODIC to reduce errors with ammunition transactions.
See Figure F-4.
Figure F-4. Example of a DODAC
(Back to Top)
F-7. The main reason ammunition is painted is to protect it from
rust. However, the color of the protective coating and markings
also makes ammunition easy to identify and provides some
camouflage. Ammunition 20mm and larger is color-coded IAW
MIL-STD 709C (see Tables F-2 and F-3). Figure F-5 shows typical
markings for an artillery round of ammunition.
Table F-2. Ammunition Color Code, MIL-STD 709C
Fed Std No 595
Identifies low-explosive items of components or
indicates low explosive. Normally brown band around
Identifies HE ammunition or indicates presence of
Identifies chemical ammunition containing toxic
chemical, incapacitating or riot control agent. Used
as basic color.
Identifies riot control agent filler.
Identifies toxic chemical agent filler. Used for
markings and bands.
Identifies incapacitating agent filler. Used for
markings or bands.
Identifies armor-defeating ammunition or indicates
Identifies countermeasure ammunition (e.g., radar
Identifies screening or marking smoke ammunition.
Identifies incendiary ammunition or indicates highly
flammable material (liquids, jellies, solids) that
produce damage by fire.
Identifies illuminating ammunition or ammunition
that produces a colored light.
Identifies practice ammunition.
be used to identify ammunition used for tracking and
recovery in tests or training operations (e.g.,
underwater mines and torpedoes).
Bronze, gold, brass
Identifies completely inert ammunition for use in
activities such as assembly, testing, handling,
drills, etc., not to be delivered in a delivery
Footnote. The following have no color-coding
Colors specifically applied to identify the color of
smoke ammunition or pyrotechnics.
2. Unpainted or natural color ammunition.
3. Gray black, green, or white on underwater
4. Gray on air-launched missiles.
5. Black or white when used for lettering or special
6. White on guided missiles, dispensers, and rocket
Table F-3. Application of Color Codes for Particular
Ammunition Items, MIL-STD 709C
Explosive binary munitions
Antipersonnel and antitank mines
With bursting charge
Without bursting charge
Filled with a toxic chemical binary nerve agent
broken dark green9,10,11
Fixed or semifixed
With low explosive to indicate functioning
With high explosive to indicate functioning
Without explosive to indicate functioning
Screening or marking
Filled with other than WP
Filled with WP
Inert ammunition not designed to be delivered in a
Filled with a riot control agent
Filled with an incapacitating agent
Filled with a toxic chemical agent other than
Filled with a toxic chemical binary nerve agent
broken dark green 9,10
1. Color of the letters and figures normally used for
the main identification.
2. Circumferential band of yellow diamond-shaped figures
on semifixed and separate-loading improved
3. Circumferential band of yellow triangular-shaped
figures on mass scatterable mine and loaded
semifixed and separate-loading ammunition.
4. Separate-loading ammunition for shipboard use has a
circumferential yellow band besides yellow
5. Bombs have one yellow band except thermally protected
bombs, which have two yellow bands besides
6. Circumferential broken yellow band (1/2-inch segments
with 1/2-inch gaps) on explosive binary
7. Circumferential band of white diamond-shaped figures
on ammunition containing flechettes.
8. Yellow band put on when the ammunition contains
explosives used to fracture the projectile.
9. Yellow band put on to indicate HE burster.
10. Toxic chemical agent ammunition containing a binary
nerve agent filling shown by a broken dark green
band (1/2-inch segments separated by 1/2-inch
11. Both color applications are standard. However, for
land ammunition use, separate-loading ammunition
is olive drab for overall body color with a
white band and main identification details marked white.
and semifixed ammunition is white for
overall body color with main identification details in
12. Separate-loading ammunition for shipboard use has
black markings and a light red band.
Figure F-5. Typical Artillery Markings
F-8. Small arms ammunition is not color-coded under MIL-STD
709C. Either the small arms projectiles or the bullet tips
are painted a distinctive color so they can be identified
quickly. Figures F-6 through F-8, show the color codes for
types of small arms ammunition up to and including.50
caliber. For more information, see TM 9-1300-200.
Significant features of the current color-coding standard
are as follows:
Olive drab. With yellow markings, OD indicates an
HE round. However, OD is also being used as a basic color
for certain new rounds such as ICMs, the flechette
antipersonnel round, and some new illumination rounds for
specific field artillery weapons.
Overpacking. Ammunition overpacked in color-coded
bombs, in unit dispensers, or in warheads, must not be
Camouflage. Ammunition containing toxic chemical,
incapacitating, or riot control chemical agents must never
be camouflaged by painting.
Standard DOD Ammunition Color Code. MIL-STD 709C
contains the standard ammunition color code for 20mm and
larger ammunition. Be aware, though, that there is still
ammunition coded as specified by MIL-STD 709-B and MIL-STD
709-A. If this is the case, see the appropriate MIL-STD or
Figure F-6 5.56mm Cartridges
F-7. 7.62mm Cartridges
Figure F-8. Caliber .50 Cartridges
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