Modern Warfare: Firearms 101 - Small Arms Ammunition
By thelizman in Technology
Sat Aug 23, 2003 at 11:47:09 PM EST
Tags: Freedom (all tags)
It's been over a year since the first multipart installment (
5) in the
Modern Warfare series has graced the queue here at K5. A few people
have asked me when I will commence with the next step in the series.
Today, I begin the first installment in Firearms 101 - Small Arms Ammunition.
This article will introduce the reader to the "cartridge" and the "shell", and will discuss types, sizes, construction, and applications.
Types of Ammunition
The two main kinds of ammunition are are the cartridge, and the
A cartridge consists
bullet, a shell casing (sometimes referred to as a casing or a shell, but
not to be too confused with the shell), a charge, and a percussion cap
(also known as the
primer cap). The percussion
cap is inserted into the base of the shell, and then a carefully measured quantity of
charge is poured into the shell. Finally, the bullet is inserted into the open end of the
shell casing, which is crimped onto the bullet.
This is known as the
center-fire cartridge, and is by far the most common bullet design.
, a pin strikes the percussion cap, which contains a small amount of explosive.
The energy of the impact is sufficient to detonate the explosive, which in turn generates
the thermal energy needed to detonate the charge. The rapid expansion of gasses accellerates
the bullet down the barrel, and out of the firearm.
While the center fire cartridge is the most common, small caliber cartridges also come in a
"rim fire" version. In this case,
the percussion cap is part of the shell. The firing pin
strikes the shell anywhere on the back to fire the catridge. Rim fire catridges cannot be
reloaded, nor can they withstand high pressures, so typically they are used for small caliber
catridges such as the .22, .22 Magnum, .22 LR (Long Rifle), .25, and the antiquated .32 calibers.
Another type of ammunition is the "shell". Fundamentally, a shell is basically a cartridge
without a bullet, where the end is crimped off. In fact, blanks, often used for training or
simulation, are made by building a cartridge without a bullet, and simply crimping the ends off.
However, shells differ in two ways from cartridges. Most commonly, shells are used
in shotguns. For starters, modern shells are made from plastic, whereas almost all cartridges
use metal (brass or steel) for the shell casing. (Older shotgun shells did use
metallic casings, but the plastic casings are less expensive to manufacture, and will
still work properly in a shotgun). Secondly, the projectiles used by shells
are placed inside the shell casing, instead of at the end of it.
The most common projectile used is "
shot", or small balls made of metal. The shot is separated from the charge by a
plastic plug. When the shell
is fired, the shot is propelled out the end of the firearm. Unlike a single bullet, the
shot spreads out proportionally to the distance covered, in what is called a "spread". This
makes shotguns more effective for hunting small, fast moving game that cannot be easily hit
with a single bullet.
In some cases, a shell will actually have a single projectile, called a slug. A slug operates
as a bullet would, albeit an exceptionally large and slow moving bullet. In other cases, the
shell will be filled with small dart-shaped pieces of razor sharp metal called "flechettes".
The shape of a flechette makes it more efficient in flight than shot, so they fly farther.
Capable of penetrating body armor, flechettes produce a more gruesome wound, and are
outlawed for combat use by the
Fourth Geneva Convention.
Catridges come in a variety of sizes, usually associated with the size of its bullet
measured by caliber.
As you may have already noticed, bullet
sizes are measured in either English caliber or metric caliber. The English measure of a caliber is a hundredth
of an inch, thus the .22 caliber bullet is .22 inches in diameter. A caliber doesn't convey
information about the length of the bullet. However, bullets that are named according to
their metric caliber do, because they are typically described by their diameter and length,
such as the 9mm x 19mm. In addition to the bullet size, the differences in cartridges also
occur in the size of the case, and the mass of the bullet, and the amount of charge.
For instance, the .50
AE is a half inch in diameter pistol catridge which measures approximately 1.25 inches in
length. The .50 BMG, on the other hand, is a half inch in diameter, but is over 5.7 inches
in length, and can only be safely fired from specially designed rifles.
The most common cartridges are:
- .22 - The 22 caliber is the smallest cartridge commercially produced. A
.22 is typically used
for target practice, small game hunting, or for instructing children in firearms
safety. A .22 is commonly used in revolvers and single-shot rifles.
- .22 LR - With the same diameter bullet as the .22, the LR - for Long Rifle - has a
longer shell casing and a more powerful powder charge. The .22 LR is used anywhere
a .22 would be used, but more power is needed. The .22 LR is typically only used in
rifles, though some hand guns have been produced to take advantage of the still
compact but more powerful cartridge. The more powerful charge also allows the .22 LR to
be used reliabily in semiautomatic rifles and handguns.
- .223 - The .223 (essentially a 5.56mm) is a powerful cartridge which uses
a small bullet propelled at very high speeds. The .223 is widely used for hunting large
game, and by various militaries as the 5.56mm x 29mm
- .25 - The .25 provides an even more powerful cartridge and a bullet with more mass than the .22,
allowing it to be used for not-so-small game.
- .3006, or 30.06 caliber - The "thirty ought six", although just slightly larger
than the .25, is a much more powerful catridge and was widely employed during World War
II. It is the most powerful of the small caliber class of bullets
. The 30.06 caliber is still widely used by
- .32 Auto - This cartridge was initially developed as an automatic pistol cartridge,
but is actually more commonly used in older Police service revolvers. Because it was underpowered,
it was unreliable for pistols, and not very well received as a revolver cartridge. 32 caliber revolvers
were cheaply produced in the 20's and 30's, so they became a standard issue firearm for
law enforcement officers who could not purchase their own sidearm.
- .357 Magnum - The .357 Magnum is one of the most powerful handgun cartridges
in mass production. Though fired from a handgun, the .357 Magnum packs more power than many
modern small caliber assault rifles. Its legendary stopping power made it a very popular
cartridge for law enforcement use, even though actual studies proved that it was not much more effective
than other more commonly available cartridge when used against "soft" targets.
- .357 SIG - This small cousin of the .357 was designed to put the power of the .357
into a cartridge suitable for semiautomatic pistols. In spite of having the same caliber, the
.357 has nowhere near the power of the .357 Magnum, but is competitive.
Notably, the .357 SIG is one of the few "necked" handgun cartridges, and the first one in
over 80 years. Necked means that the diameter of the cartridge is larger than the diameter of the
bullet, with the cartridge being the size of the .40 S&W.
- .380 - Also known as the "9mm Short", the .380 is a .38 caliber cartridge designed for
automatic pistols. The .380 can be used in 9mm pistols, although it usually is not as reliable as the
round the pistol was designed to use.
- .38 Special - Th .38 caliber cartridge is a popular round because it provides a
respectable degree of stopping power, but in a compact case which inspired equally
compact revolvers. This made 38 caliber handguns easy to conceal, which had a dual edged
benefit. On the one hand, the .38 Special became known as the "Saturday Night Special",
because they were cheaply made, easily concealed, and thus became a common firearm used
in robberies and muggings. By the same token, the .38 "Snub Nose" became popular as a backup
weapon for the police community, because it could be concealed in a back pocket, or in
increasingly popular ankle holsters.
- .40 S&W - The .40 Smith & Wesson starts the large caliber category, and is also one
of the newest cartridges in use. It was developed as a bridge between the popular 9mm bullet,
which typically allowed higher capacity magazines, and the powerful .45 ACP. The development
of the .40 S&W followed an investigation into
a shootout between FBI Agents and robbery suspects in which it was determined that the
standard issue 9mm handguns were not powerful enough take down the suspects, who were armed
with more powerful .357 handguns and .223 assault rifles.
- .44 S&W - The 44 Caliber Smith & Wesson is a revival of the classic .44 caliber.
During the late 19th and early 20th century, a number of gun makers began to experiment with
the incredibly popularized .44-40 cartridge made famous by the cowboys and outlaws who
used them. The .44-40 was an overstatement in terms of its power, so gun makers devoped cartridges
they could call .44 caliber, but that would fit their existing frames. The .44 S&W is actually
43.4 caliber, and was designed for the
Model 3 break action revolver frames.
- .44 Magnum - This is the infamous "Dirty Harry" catridge. The .44 Magnum,
like the .44 S&W, was designed to bring the mystique of the
.44 to an existing frame. Also, since "Magnum" means big, it allowed owners of .44 Mags to gloat
over other .44 owners, since their bullet was actually 44.3 caliber. The .44 Magnum is
also known as the most famous pistol that used it, the .44 Colt.
- .45 ACP - The 45 caliber is the progeny of the legendary John Browning, who developed the
cartridge for use with his Model 1911. Though the 1911 initially used a .380 cartridge as
manufactured by FN, Colt
was trying to sell the 1911 to the US Army, who was only interested in large caliber
handguns. Browning chose the .45
caliber bullet both for its ballistic properties, and because it was larger than the
common .44 caliber rounds the Army used in their revolvers. ACP stands for Automatic Colt Pistol
- .50 AE - The 50 caliber Action Express was developed by Action Arms on
contract with Israeli Military Industries to "increase ballistic performance". In
short, IMI was looking for a handgun with the power to definitively defeat body armor.
The .50 AE was made famous by the
Desert Eagle .50, and is featured prominantly in
such movies as "Snatch", or as used by
Agent Smith in "The Matrix".
- .50 BMG - The 50 caliber Browning Machine Gun cartridge is the most powerful cartridge
commercially manufactured. So powerful in fact, that there are only a handful of man-portable
firearms which can fire the round. Typically, the .50 BMG is used on crew served weapons.
- 5.56mm x 45mm NATO - Equivalent to the .223, this is the standard cartridge for
the assault rifle and automatic rifle in NATO countries such as the US. The 5.56 is a
high velocity round capable of piercing lightly armored vehicles, and is fairly
accurate. However, the high velocity has the draw back of creating clean wounds with
tapered bullets that
do not immediately incapacitate. This is the round used by the US M-16.
- 7.62 x 39 BLOC - The standard round of most Kalishnikov assault rifles, the 7.62x39 is
a versatile round which has the stopping power and accuracy to fill a wide variety of roles.
This cartridge is easily the most popular in the world, since it is used in every AK-47, AK-74,
and subtypes of those two Russian rifles.
- 7.62 x 51 NATO - This cartridge is commonly used on machine guns, where long distance
accuracy in addition to a powerful bullet is required. The 7.62 x 51 is capable of accurate
fire from most weapons out to 3/4 of a mile, and can engage light armored vehicles effectively
at less than 100 yards.
- 7.62 x 54 BLOC - This cartridge is the Soviet answer to the 7.62 x 51, and is used
in light machine guns. The 7.62 x 54 is slightly more powerful because of its mass and increased
cartridge length, and is also sometimes used in sniper rifles.
- 9mm Makarov - Measuring 9mm x 18mm, the 9mm Makarov is used in older pistol cartridges and
Soviet Block handguns.
- 9mm Parabellum - Measuring 9x19, the 9mm Parabellum (aka the 9mm Luger)
is a powerful high velocity round,
but because of its ballistics, it tends to leave cleaner wounds. 9mm's were largely abandoned
for law enforcement use because of this, but has seen some persistance due to its favored
use in sub machine guns, where the smaller cartridge means higher magazine capacities. The
9 has also been glorified in pop culture through references in gangster rap.
- 10mm - The 10mm is a popular alternative to the 9mm, and is essentially an
elongated .40 S&W cartridge. The 10mm was developed in the early 80's by Dornhaus and Dixion
for use in their Bren Ten automatic pistol.
This is by no means a complete list of cartridges, but merely represents the most common.
Some of the rarer and more extravagant types, such as the Wildey .475 Magnum were left of
because of their near exclusive use in a few rare firearms.
Shells are less diverse than cartridges, owing partly to the fact of their limited use in
shotguns and combination shotgun/rifle firearms. Unlike cartridges, shells are measured in
"gauge", and commonly available in 8, 10, 12, 16, 20 and 28 gauge sizes. The gauge is the
diameter of the shell. The length of the shell is specified simply in inches, and typically
come in 2 3/4 inch, 3 inch, and 31/2 inch shells.
The exception is the .410 gauge, which is actually a 41 caliber shell. Aside from the .410,
all shells used in firearms are used in long guns. The .410 can also found in
Derringers and revolvers, but largely for novelty and collectible purpouses.
One more consideration in a shell is the type of shot,
itself measured in a gauge different
from that used to determine the shells size. The size of the shot is related to its use.
Very small shot is typically used for hunting fowl, or for blowing the locks off doors (special
frangible materiel is used for this purpose). Larger shot is used for game hunting,
the largest being 00 ("double aught") buck shot, which is used for hunting Deer. Specially
shaped shot called "slugs" are also used, delivering the power and punch of a very large
caliber bullet. A 12 gauge slug is equivalent to a 73 caliber bullet.
While there is a wide variety of cartridges, there is a comparatively small variety of
bullets. Bullet technology has remained essentially unchanged since bullets evolved from
ball musket shot to the commonly accepted tapered bullet shape.
For starters, there is a small deviation in bullet shapes. Typically, bullets will either
be ball or tapered. Ball ammunition is exactly what it sounds like. Either the bullet is a
complete ball, or it is a cylinder that is tipped by a ball. Ball ammo has very poor aerodynamic
performance at high speeds, and is rarely used in rifles where accuracy is of great concern.
Because of the blunt end of ball ammo, it transfers more of its energy to the target on impact.
By contrast, tapered ammo is very aerodynimically efficient at high speeds. Tapered bullets
are almost the exclusive bullet of rifles. Although they do not transfer as much of their energy
to targets on impact, tapered bullets are designed so that when
they strike a target, they begin to tumble causing a large "wound channel". For
marksman competition use, bullets are balanced on their center of pressure to
maximize stability. In addition, marksman style bullets are boat-tailed - that is they are
slightly tapered at their back end in order to improve aerodynamic flow and prevent drag
inducing eddies behind the bullet.
Less common is the "semi-wad cutter", or "flat tip" bullet. These are typically used for
target practice, and with handguns. The flat tip produces a clearly defined hole in a
paper target, allowing a shooter to gauge their accuracy from afar. Typical ball or
tapered ammo will produce a hole smaller than the bullet itself, with tears radiating from
the center. These are difficult to see beyond about 10 yards.
Pistol ammunition can also have "hollow points". A hollow point is where the tip of the bullet
is burrowed out. While this makes the bullet lighter, it promotes expansion and fragmentation of the bullet on
contact with a target, making even low power bullets very damaging.
Other bullet designs have experimented with cross-cut tips, which provide the fragmentation of a hollow point with the stability of a solid tip for higher velocity pistol rounds. There is a
slight danger of hollow points fragmenting in flight, which is why they are rarely - if ever -
used on rifle cartridges. Yet another bullet design was the subject of great controversy - the
Black Talon, which consisted of a pyramid shaped bullet tip. Although this tip had no greater
impact than a standard tapered tip, it was advertized as an armor piercing bullet which led
to it being labelled "the cop killer bullet". Although it was legal under Federal Law,
The manufacturer pulled the design from the
market, but licensed the design to other manufacturers, and the black talon-styled bullet
is commonly available under a Talon name, but widely considered not worth the expense.
Most bullets are jacketed - that is the solid bullet is coated. That is because the majority of
bullets are made from lead, which is used for its density. However, being a soft material,
lead tends to deform heavily changing its ballistics. A jacket is applied to stabilized the
bullets ballistics. Manufacturers have experimented with various amounts of jacketing, from
partial jacketing of the rear of the bullet, to full jackets which cover the bullet from tip
to tail, and in between. Another benefit of jacketing is that it reduces the amount of
lead the shooter is exposed to. Lead, even in small amounts, is toxic and can cause health problems
(up to and including death, which is kind of ironic).
Finally, there have been recent developments that redesign the bullet itself. New bullets called
are made by compressing metal powders into a solid bullet. Because the
granules of powder are not molecularly bonded, the bullet fragments on impact with solid surfaces.
This means a reduction in accidental shooting where the bullet ricochets, or passes through its
intended target. Frangible bullets received much attention in the post 9/11 debate over arming
Sky Marshalls and airline pilots. Other technologies include gelatin bullets, which improve upon
the rubber bullet by delivering a heavy stun, but being far less likely to be lethal than
traditional rubber coated bullets which can kill. Less than lethal technologies will not be discussed
in this series of articles.
The selection of a cartridge is as important as the selection of a weapon. Characteristics
such as accuracy, take down power, and portability are considered when selecting a firearm at a
given caliber. Special purpouse ammunition can also be employed to accomplish particular phases
of a mission, without requiring a change in weaponry. In the next article, we will discuss
firearm types, and their employment in the field.