| +P:
Designates that ammunition that is loaded to a higher
pressure. This is usually marked on the cartridge case.
Use this ammo only in firearms specially designed for
these higher pressures as recommended by the gun's
manufacturer. +P+: Ammunition loaded to even
higher pressure than +P. Again, use only in guns
specially designed for this load. Typically used in
defense situations and not for target shooting or
general plinking.
ACP: Abbreviation for "Automatic Colt Pistol",
a line of cartridges of which the most popular is the
.45 ACP.
Action: The combination
of parts of a firearm that perform loading, feeding,
locking, firing, unlocking, extracting, and ejection.
This term evolved from the original concept of a
lock, which just referenced to the
firing mechanism.
Alox: A petroleum product consisting of
calcium and mineral spirits. Often mixed with beeswax
and used as a bullet lube.
Anvil: A metal component within the primer or
an integral part of the cartridge case against which the
priming compound is compressed as the firing pin or
striker impacts the exterior face of the primer cap.
This sudden, violent compression of the priming compound
causes it to ignite. Boxer
primers have the anvil in the primer;
Berdan primers have the
anvil as an integral part of the cartridge case.
Assault weapon:
Slang term created by gun control advocates to demonize
firearms and used to describe an automatic or select
fire military rifle firing an intermediate-power
cartridge. Assault weapons are no more powerful (often
less powerful) than ordinary hunting rifles. The primary
difference between hunting rifles and assault weapons is
mere appearance.
Assault rifle: A combat rifle developed by the
Germans during WWII (called Sturmgewehr), these rifles
were made principally by Walther and Haenel. They
offered mid-range power for troops requiring a compact
rifle. See assault weapon.
Automatic: An action that chambers, fires and
ejects each cartridge in succession with one pull of the
trigger. As long as the trigger is held down, the gun
continues to fire until all ammo has been expended.
Ball: The original
spherical ammunition used in
muzzleloaders. Another name for
bullet (generally military jargon: "ball"
ammunition) as opposed to shot.
Usually describes a full metal jacket bullet. Used by
Olin industries to describe their spherical
powder.
Ballistics: The science of projectiles in
motion. Usually divided into three parts: 1.) Interior
Ballistics, which studies the projectile's movement
inside the gun; 2.) Exterior Ballistics, which studies
the projectile's movement between the
muzzle and the target; and 3.) Terminal Ballistics,
which studies the projectile's movement in the target.
Barrel: That portion of a
firearm that includes the chamber
and the bore and through which a
projectile travels. As the
powder burns in the chamber, a
projectile is pushed down the barrel and out the
muzzle. The barrel may be
rifled or
smooth bore.
Belted magnum: A cartridge that has a
prominent belt forward of the base. The headspace is on
the belt rather than the rim or shoulder of the
cartridge. Belted magnum cartridges are usually higher
power.
Berdan primer:
Cartridge ignition method
invented in 1866 by Hiram Berdan, a Civil War-era
ordnance officer, inventor and Sharpshooter. This primer
system uses 2 or 3 smaller flash holes that are
off-center. They are unpopular with reloaders because
they're difficult to remove from cartridges, unlike
Boxer primers, which have a central flash hole. Berdan-primed
ammo is more popular outside the US and is generally
found in non-US military surplus ammo.
Birdshot: Ammo that is a small metal ball.
Used for hunting birds or small game. Generally made of
lead and varies from BB (larger) to #12 (smaller) shot
sizes.
Black powder: Originally called gunpowder,
it's now called black powder to distinguish it from the
more modern smokeless powder. Often abbreviated BP, it's
a mixture of potassium nitrate (saltpeter), sulfur and
charcoal. Less powerful than smokeless powder, it
produces more fouling (deposits) and a large amount of
smoke when ignited. Used widely in sporting guns and
blasting. Can be ignited by a spark, static electricity,
heat or a sharp blow.
Blowback action: An action
characterized by a system where when the firearm is
fired, the weight of the hammer,
slide, recoil spring, and other parts combine to keep
the action closed. No mechanical locking system is used.
Found in automatic and semi-automatic firearms.
Bolt: The part of a firing
mechanism which contains the
firing pin assembly and
extractor mechanism. It rotates to lock the
cartridge or
shell in the firearm's
chamber during firing.
Bolt-action: An
action that resembles a common
door bolt (hence, the name). Utilizes a manually cycled
bolt system. The most common type utilizes a cylindrical
bolt with a bolt handle that is used to rotate the bolt
body 45 to 90 degrees in order for it to unlock from the
breech and be manually opened and closed. Cycling the
bolt ejects a spent cartridge, loads a fresh one (if available) and
cocks the rifle.
Bore: The inside of the
barrel.
Bottleneck cartridge: A
cartridge case having abrupt
reduction in its diameter toward its open or mouth end,
often called the 'shoulder' of the cartridge. This
permits large case capacity without making the case
overly long.
Boxer primer: A
primer invented in 1867 by
British Colonel Edward Boxer. It's easier to remove from
a spent cartridge, making it a favorite of reloaders and
American ammunition manufacturers.
Brass: See case.
Breech: The rear of the barrel. It depends on
the model of gun to determine the breech area. It can
contain the chamber, be a simple reference to the back
of the barrel or just be the action behind the barrel.
Buckshot: A small round
lead bullet or large
shot used in hunting large game.
Lead pellets ranging in size from .20” to .36” diameter
normally loaded in shotshells.
Bullet: The
cartridge component which, when
in flight, becomes the projectile,
usually made of lead and sometimes covered with a jacket
of copper alloy or other metal. Sometimes mistakenly
used to describe ammunition.
Buttstock: The rear
most part of a rifle or
shotgun stock. It rests against the shooter's shoulder.
Caliber: The diameter of a projectile or
barrel measured in inches or millimeters.
Carbine: A short rifle. There is no
established length for a carbine.
Cartridge: A loaded round of ammunition that
includes the case, primer,
powder charge and
projectile.
Case: The component of ammunition that
contains the primer,
powder charge and
projectile. Rifle and handgun
cases are usually made of brass (hence thier other
common name - "brass") but steel and aluminum are also
common. Shotshell cases (hulls)
may be all plastic, all brass, or (most commonly)
plastic with a brass head. Older shotshells were made of
brass and paper.
Centerfire: Any
cartridge that has a
Berdan or
Boxer priming system. Also refers to any firearm that
uses centerfire cartridges.
Chamber: A cavity in a firearm that accepts a
cartridge. It may be found in the
barrel or, in the case
of revolvers, in the separate
cylinder. The act of inserting a
cartridge into the chamber.
Choke: A reduction of the bore diameter at the end
of a shotgun barrel that changes the pattern/spread of
shot as it leaves the gun. Some shotguns have screw-on,
interchangeable chokes. Some target rifle barrels are
constricted at the end, and that is also called a choke
- it stabilizes the bullet before it exits the
muzzle.
Chuck Hawks' Choke page.
Clip: A clip is any type of
cartridge-holding device used
to load magazines (either fixed
or detachable). Also known as a 'stripper clip' in
military jargon, and as a 'charger' in England. The
first successful cartridge clip was invented by Austrian
engineer Ferdinand von Mannlicher. Magazines are often
erroneously called clips.
Cock: A verb meaning to make a
gun ready to fire, i.e., to cock. Also a mechanical
portion of a flintlock or other old firearm
lock.
Crown: A cut applied to the
muzzle of a barrel to
ensure that the projectile's base exits evenly from the
rifling. Different types of crowns result in different
levels of accuracy.
Cylinder: The revolving section of a firearm
that holds cartridges. It rotates to index each
cartridge with the barrel so it can be fired.
Damascus barrel: Barrels
manufactured using strips of iron braided and forged
together. Not safe for use with modern ammunition.
Decocker: A lever that safely releases the
hammer's spring tension and makes a gun
uncocked.
Double-action: A function that lets the
trigger cock the
hammer and release the
sear, which
results in firing the gun. See
single-action.
Dram: A unit of weight equal to 27.344 grains
or 0.0625 ounce.
Ejector: A mechanism that kicks out a spent
case from the chamber.
Elevation: An adjustment mechanism that lowers
or raises the sight to change the
point of aim, which
then changes the point of impact.
Extractor: A mechanism that pulls a spent
case
from the chamber.
Firing pin: A device that strikes the
primer
and causes ignition, which then travels to the main
powder charge and ignites it.
Flash-hider: Shields the shooter's eyes from
the powder flash at the muzzle so he is not blinded by
the sudden bright light when firing. Most useful at
night to help the shooter preserve his night vision. On
military arms, it prevents enemy forces from locating
the shooter.
Flintlock: A type of firing mechanism in
muzzleloading firearms. Flint is used to strike a
frizzen (piece of steel), which results in a spark that
ignites the priming charge (a small pan of powder). The
priming charge shoots flame through a small hole in the
breech to ignite the main charge.
Forend: The portion of the
stock located
forward of the action. Also called
forearm.
Fouling: Build up of bore residues such as
powder, copper, lead and wax. These deposits accumulate
in the bore because of high heat during firing. Fouling
accumulation may cause a decrease in accuracy.
FPS: Feet per second. The unit of measurement
for the velocity of a projectile.
Frame: Also known as the
receiver, this is the
part of a gun that houses the action.
Full-automatic: A term for an automatic
action.
Gas-operated: A semi-automatic
action that
bleeds gasses from a fired cartridge. When the
projectile passes the gas port (a hole) in the
barrel,
the gasses are vented into a chamber and cycle the
action for the next shot.
Gauge: Designates the caliber of a
shotgun and
shotgun ammunition. Gauge is determined by the number of
bore-sized lead balls that add up to a pound in weight.
Grain: A unit of weight for bullets and
balls
that is derived from ancient agriculture. It is equal to
the average of the grains taken from the middle of ears
of wheat. A pound is 7,000 grains. One grain is equal to
.0648 grams.
Groove: The
bore diameter of a
rifled barrel.
The lands (the portion that sticks up) define the
boundaries of the grooves.
Gunpowder: Propellant
used in small arms. can be either
smokeless or
black powder.
Hammer: Part of a gun that strikes either the
firing pin or the
primer.
Handgun: A firearm
designed to be held and fired with one hand. Also called
pistol.
Hangfire: A delay in the ignition of a
cartridge's
powder charge or
priming system of a longer time
period than is standard.
Headspace: The tolerance above the dimensions
of the cartridge that is necessary for the gun to
function properly. Too little headspace can result in
difficult chambering. Too much headspace can cause the
cartridge case to stretch and even burst.
Hull: Though generally used
as a reference to any cartridge case,
it is most commonly used to denote an empty plastic
shotgun shell.
Iron sights: Common term for non-optical
sights found on a firearm.
Land: A raised ridge in the
bore of a rifled
barrel that engraves the
bullet and imparts a spin. The
lands of a barrel define the bore-sized grooves.
Length of pull: The distance in a long gun
from the trigger to the end of the
buttstock, buttpad or
recoil pad. Measured in inches, it varies from gun to
gun and from manufacturer to manufacturer.
Lever-action: A mechanism that operates the
bolt of the rifle. It performs the same functions as a
bolt in a bolt-action, but it is smoother.
Lock: The firing mechanism of a gun (usually a
muzzleloader). Common types of locks include matchlock, wheelock,
flintlock and
percussion lock. Today's
actions
are also called locks.
Machine gun: A gun that sequentially fires multiple rounds
with one pull of the trigger.
Magazine: The part of a firearm (often
removable) that holds cartridges until they are fed into
the chamber. Magazines are often erroneously called
clips.
Magnum: A designation for increased
cartridge
velocity and energy due to higher levels of powder,
e.g., .38 Special to .357 Magnum and .44 Special to .44
Magnum.
Misfire: A condition caused by ignition
failure. Also called a "dud."
MOA: Minute of angle. Describes the level of
accuracy of a gun. If a gun shoots a 1" group at 100 yds.
and a 2" group at 200 yds., it shoots 1 MOA. It also
describes the width of a scope reticle. For instance, if
a scope's reticle or dot is 4 MOA, it covers 4 inches at
100 yds.
Moly: See Molybdenum disulfide.
Molybdenum disulfide: A very slick compound
that is used in many places in firearms. Some ammunition
is coated with moly. May increase velocity and accuracy.
Musket: A general term
used to describe all
muzzleloading, smooth-bore
long guns.
Musketoon: A short-barreled
musket.
Muzzle: The end of the
barrel.
Muzzlebrake: A device that attaches to the
muzzle. Has vents or ports on the side or top to direct
gasses up and to the side to reduce felt recoil and
muzzle rise.
Muzzleloader: A firearm that is loaded by
ramming (pushing) the projectile into the gun from the
muzzle and down the
barrel.
Muzzle velocity: The speed of a
projectile as
it exits the muzzle. The unit of measure is feet per
second (fps).
Over-and-under: A type of long gun having 2
barrels, with one stacked on top of the other. Can be a
shotgun or centerfire
rifle or a combination of these
two. Often designated O/U.
Percussion: The act of detonating a
percussion
cap in a firearm. Also designates a type of firearm
lock.
Percussion cap: A thin metal cup containing an
explosive substance, such as fulminate of mercury, that
explodes when struck.
Percussion lock: A
lock that uses a
percussion cap
to ignite the gunpowder.
Pistol: See handgun.
Point of aim: Where the
sight of gun indicates
the projectile is supposed to land.
Point of impact: Where a fired
projectile
actually lands.
Powder: See gunpowder.
Powder charge: The
main charge of propellant granules that are ignited in
order to create the expanding gases in a bore to propel
a bullet or shot
charge forward.
Primer: A cap or tube with a small amount of
explosive. Used to ignite the main
powder charge of a
cartridge.
Projectile: Anything
discharged from a firearm, including a
bullet, shot pellets, a
wad and burnt
powder.
Proofmark: An acceptance mark given to a
firearm that has successfully passed a test by firing
one or more high-pressure loads.
Pump-action: A cocking mechanism that uses a
back stroke of the gun's forearm to eject a spent
cartridge and a forward stroke to automatically
chamber
a new cartridge. Also called slide-action.
Receiver: Also known as the
frame, it houses
the action of a gun.
Revolver: A gun
(usually a handgun) with a cylindrical
magazine
that holds cartridges or
gunpowder and
projectiles.
Operating the gun causes the cylinder to rotate, which
puts a fresh cartridge or load in line with the
barrel.
Rifle: A shoulder-mounted
firearm, normally with a barrel
over sixteen inches in length, with a
bore that contains rifling.
Rifling:
Grooves alternating with
lands inside
the barrel of a gun. See
twist rate.
Rimfire cartridge: Ammunition that has its
primer charge in the rim of the base. When the firing
pin strikes the rim, it detonates the priming charge,
which ignites the main charge of gunpowder. Firearms
using this type of cartridge are called rimfires.
Sabot:
A lightweight cup-like cover placed
around a projectile enabling it to be fired in a
bore of
larger diameter.
Safety: A device that prevents a gun from
firing.
Sear: A catch in a gun's
lock that holds the
hammer or firing pin
in the cocked position.
Semi-automatic: Usually shortened to semi-auto
and sometimes called a self-loader, this type of action
automatically ejects a spent cartridge and loads the
next one through the energy of the previously fired
cartridge. It fires one cartridge with each pull of the
trigger.
Shot: Round balls or
pellets (usually made of metal) used
in shotgun shells. The pellets vary in diameter but are
uniform within one shotgun shell. They are given numbers
or letters to designate their size. Larger shot has
lower numbers (such as 4 and 5), and smaller shot has
higher numbers (such as 8 and 9). See
buckshot.
Shotgun: A gun without a
rifled barrel (also
called a smoothbore) that fires
shot or slugs over a
shorter range than a rifle. Also known as a scattergun.
Shotshell: A
cartridge used in a
shotgun.
Side-by-side: A common term for a
double-barreled gun, most often a shotgun.
Sights: A means of reference that guides the
shooter when aiming the firearm. Modern firearms
usually have attached sights.
Single-action: A
trigger mechanism that
performs just one action, which is releasing the
hammer
after it has been cocked. This differs from
double-action, where a
single pull of the trigger cocks the gun
and fires it.
Slug: A round
projectile larger than
buckshot
and used for short-range shooting. Also, a slang term
for a bullet.
Smokeless powder: The successor to
black
powder. It was developed to be safer and more potent,
plus it does not produce as much smoke as black powder.
Although smokeless powder is often black in color, it
must never be confused with black powder.
Smoothbore: A
barrel without
rifling. A firearm that utilizes a barrel without
rifling such as a common shotgun
or a musket.
Speedloader: A device that eases or speeds up
the process of reloading a revolver. It can load an
entire cylinder in the same period of time that it takes
to load one cartridge.
Stock: The wooden, plastic
or metal part of a long gun that contains or holds the
barreled action.
The stock allows the shooter to hold and aim the firearm
by bracing it against the body. A
forend stock provides a forward hand hold. On
handguns, the panels on the sides
of the grip are also known as stocks.
Submachine gun: A lightweight automatic gun
that shoots pistol ammunition.
Trajectory: The path of the
projectile from
the moment it leaves the gun until it hits a target.
Trigger: The mechanism that fires a gun.
Trigger pull: The amount of force that causes
the sear to release.
Twist rate: The distance (in inches) required
for a barrel's rifling to turn one revolution. For
instance, 1:9 means the rifling makes one revolution in
9 inches.
Wad: A
shotgun shell component that, while as wide in
diameter as the hull, can vary in
height. Used to separate powder
from shot. Various types of wads
exist, the most commonly used in modern shotshells being
the powder wad, a column of plastic that sits on top of
the powder charge and has a cup or flat surface that the
shot charge rests on.
Wadcutter: Cylinder-shaped bullet with flat
ends. Designed for target shooting because it makes
clearly defined round holes that are easier to score.
Windage: A sight adjustment that moves the
point of impact either right or left.
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