Gunsmith
Glossary
A
ACCURIZE
(accurizing): The process of
altering a stock firearm to improve its accuracy.
ACTION:
The physical mechanism that manipulates cartridges
and/or
seals the breech.
The term refers to the method in which cartridges are loaded, locked,
and extracted from the mechanism. Actions are generally categorized
by the type of mechanism used. Action is not present on muzzleloaders
because all loading is done by hand. The mechanism that fires a
muzzle-loader is called the lock.
Typically, firearms are single-action and double-action.
Single-action uses manually cocked hammer, while double-action
operation automatically cocks and releases the hammer by way of the
trigger [two-stage operation].
ACTION,
AUTOMATIC: Type of firearm that delivers continuous
loading, firing, and cartridge ejection while the trigger is
depressed. Machine guns employ automatic action. Possession of
automatic firearms by civilians requires special permission and
licensing via the Department of Treasury, ATF Department.
ACTION,
BOLT: Type of firing action that requires manual loading
[or a small capacity magazine], manual hammer-cocking, and unloading.
Unloading and loading is performed by retracting the bolt mechanism,
which ejects the used cartridge and allows for the insertion of
another. Bolt action rifles deliver good accuracy, which makes them
popular for hunting, competition sports, and military snipers.
ACTION,
LEVER: Similar
to bolt
action,
this mechanism uses an external lever, placed directly below the
receiver to load new cartridges, cock the hammer, and unload spent
cartridges. Several models of rifles use lever action, as well as Old
West shotguns like reproductions produced by Uberti.
ACTION,
PUMP: This firing mechanism employs a sliding firearm that with a
single pump chambers a new round and ejects the spent round. Once the
forearm has been pumped, no cocking is required for the next
discharge. Some models of shotguns are pump action.
ACTION,
SEMI-AUTOMATIC: A firearm mechanism used on self-loading firearms
that delivers a complete firing cycle that includes loading, firing,
and discharging of the spent cartridge with each depression of the
trigger.
B
BACK
BORE or
BACKBORED BARREL:
A shotgun barrel whose internal diameter is greater than normal for
the gauge. This is done to reduce recoil, improve pattern, or change
the balance of the shotgun.
BACKSTOP:
The barrier behind the target at the range that stops bullets.
The area shoud be free of debris, especially rock and metal to
prevent ricochets.
BALLISTICS:
Scientific
field dedicated to the physics of projectile launch and projectiles
in motion. Interior ballistics focuses on movement inside the
firearm; exterior ballistics focuses on movement through the air; and
terminal ballistics focuses on movement through the target.
Ballistic-expert forensic scientists use their knowledge to match
bullets and cartridges
with
the "signatures" of individual firearms.
BANDOLIER
or BANDOLEER:
A pocketed belt for holding ammunition cartridges, usually slung over
the shoulder and across the chest. Bandoliers can still be found, but
magazines have made them obsolete and are only used with shotguns to
carry shells.
BARREL:
A metal tube through which a controlled explosion or rapid expansion
of gases are released in order to propel a projectile out at the end
at high velocity.
BALLISTIC
COEFFICIENT or
BC:
A measure of projectiles ability to overcome air resistance in
flight. BC is a function of mass, diameter, and drag
coefficient.
In bullets it refers to the amount of drop over distance and wind
drift that affects the bullet.
BENCHREST:
A specialized, stable stand, platform, or table used by a shooter
to support the limbs and body and steady the aim. Commonly used for
sighting in a firearm and testing accuracy. Benchrests are also used
in competition shooting events.
BIG
BORE: Generally a term used to refer to ammunition for handguns
that are higher than .38 caliber and rifles .30 caliber and higher.
In the United Kingdom it refers to rifles with .40 caliber and
higher.
BIRDSHOT:
Type of
shotgun shot loaded into shotshells that consists of small pellets
[less than .10 inches in diameter] made from lead or steel. This shot
is intended for hunting bird and small game.
BLACKPOWDER
[GUNPOWDER]:
A mixture of sulfur, charcoal, and potassium nitrate. It burns
rapidly, produces a volume of gas that is carbon dioxide, water, and
hydrogen with a residue of potassium sulfide. It is used in firearms,
pyrotechnics,
and various explosive devices. Modern firearms used smokeless
powder that
burns cleaner and with less smoke.
BLOWBACK:
A system of operation for self-loading firearms that obtains power
from the motion of the cartridge case as it is pushed to the rear by
expanding gases created by the ignition of the powder charge.
BLUING
or
BLUEING:
A passivation
process in which steel is partially protected against rust, and is
named for the blue-black appearance of the resulting protective
finish. [See Parkerizing]
True gun bluing is an electrochemical conversion coating from an
oxidizing chemical reactions with iron on the surface selectively
forming magnetite
(Fe3O4),
the black oxide of iron. Black oxide provides minimal protection
against corrosion, unless also treated with a water-displacing oil
[Break-Free]
to reduce wetting and galvanic
action. “Cold” bluing is generally a selenium dioxide based
compound that colors steel black, or more often a very dark gray. It
is a difficult product to apply evenly, offers minimal protection and
is generally best used for small repair jobs and touch-ups. “Hot”
bluing is an alkali salt solution, referred to as “Traditional
Caustic Black” that is elevated to a temperature between 270° to
310°F [135-154°C]. This method is an expensive process and was
adopted by larger firearm companies for large scale bluing by volume
in order to achieve economical bluing. It does provide good rust
resistance, but the chemicals are highly caustic. “Rust Bluing”
is best for rust and corrosion resistance because the process
converts any metal that is capable of rusting into magnetite.
Treating with an oiled coating enhances the protection offered by the
bluing. This process is the only process to safely re-blue vintage
shotguns. Many double barreled shotguns are silver
brazed
together
and many of the parts are attached by that method. The higher
temperatures of other processes as well as their caustic ingredients
can weaken the brazed joints and make the shotgun hazardous to use –
only if the brazing has been weakened.
BOLT
ACTION: A
type of firearm
action in
which the weapon's bolt is operated manually by the opening and
closing of the breach
[barrel]
with a small handle. As the handle is operated, the bolt is unlocked,
the breech is opened, the spent shell casing is ejected, the firing
pin is cocked, and a new round/shell [if available] is placed into
the breech and the bolt closed.
BOLT
THRUST
or
BREECH
PRESSURE:
The amount of rearward force exerted by the propellant gases on the
bolt
or
breech
of
a firearm
action
or
breech when a projectile is fired. The applied force has both
magnitude and direction, making it a vector
quantity.
BORE:
Interior portion of the barrel that does not include the chamber.
It may be smoothed or rifled.
BORE
DIAMETER: The
diameter of a gun barrel's interior. In rifled barrels the
measurement is from the highest point of the spiraled grooves.
BORESIGHT:
Crude adjustments made to an optical firearm sight, or iron sights,
to align the firearm barrel and sights for shooting accuracy. This
method is usually used to pre-align sights, which makes zeroing [zero
drop at XX distance] much faster. Used by manufacturers who install
and include optical sights with firearms purchased out of the box.
BORE
SNAKE: A tool used to clean a
barrel of a gun, basically a rope with a pull handle on one end and a
device for attaching a cleaning tip, commonly used for field cleaning
in a field cleaning kit.
BRASS:
Empty cartridge case, commonly made of brass, but some national
military rounds are steel but are still referred to as brass.
BREAK-ACTION:
A firearm whose barrels are hinged, and rotate perpendicular to the
bore axis to expose the breech
and allow loading and unloading of
ammunition.
BUCKSHOT:
Type of shotgun shot loaded into shotshell cases and consist of
large lead pellets that range from .20 to .36 inches in diameter. The
load is intended for hunting deer and large-game.
BULLET,
ARMOR PIERCING: A
firearm projectile designed to penetrate armor. Manufacture and sale
of armor piercing bullets for non-military and law enforcement use is
prohibited by the Gun
Control Act of 1968.
BULLET,
HOLLOW POINT: A type of bullet designed to expand upon impact,
which lessens the depth of penetration. Typically used by law
enforcement for self-defense and by hunters to avoid over-penetration
and thereby reducing the chance of innocent people being hurt by
bullets passing through the body of target.
BULLET,
WADCUTTER: Bullet
designed for target shooting with a cylinder shape and pointed nose,
it cleanly perforates target paper, leaving behind a clear,
identifiable entry point ideal for precise scoring.
BULLPUP:
a firearm configuration where both the action and magazine are
located behind the trigger.
BURST
MODE: a firing mode enabling the shooter to fire a predetermined
number of rounds with a single pull of the trigger. The M16-A2 fires
a burst of three rounds in burst mode when
selector is turned to BURST.
BUTT:
The rear end of a
firearm, opposite to the muzzle. It is the bottom portion of the
handle on handguns and the end of the stock on shotguns and rifles.
BUTTON
RIFLING:
Rifling
that
is formed by pulling a die
made
with reverse image of the rifling [the “button”] down the
pre-drilled bore of a firearm barrel. See also cut rifling
and
hammer
forging.
C
CALIBER
or
CALIBRE:
(1) in small arms, the internal diameter of a firearm's barrel or a
cartridge’s bullet, usually expressed in millimeters or hundredths
of an inch; in measuring rifled
barrels
this may be measured across the lands [as .303
British] or grooves [as .308
Winchester]. (2) A specific cartridge for which a firearm is
chambered, as .44
Magnum. (3) in artillery, the length of the barrel expressed in
terms of the internal diameter, for example, a 3-inch, 30 caliber gun
would have a barrel 3 inches in internal diameter and 90 [30 times 3]
inches in length.
CARBINE:
(1) a shortened version of a service rifle, often chambered in a less
potent cartridge. The M4
Carbine is an example which uses the same cartridge but a shorter
barrel, whereas the M1
Carbine is an example using a different cartridge. (2) a
shortened version of the infantryman's musket or rifle suited for use
by cavalry troops.
CARTRIDGE:
the
assembly consisting of a bullet, gunpowder, shell casing, and primer.
When counting, it is referred to as a round.
CARTRIDGE, MAGNUM: A
specially designed cartridge that produces greater bullet velocity,
or a shotshell containing more shot than standard for a firearm.
CARTRIDGE, RIMFIRE: A
complete, single round of ammunition with the primer located within
the metal rim of the casing. Commonly .22 rifles use rimfire
cartridges.
CASELESS
AMMUNITION:
a type of small arms ammunition that eliminates the cartridge case
that holds the primer, propellant, and projectile together as a unit.
CASKET
MAGAZINE: a
quad [four] stack box magazine.
CENTERFIRE:
a
cartridge in which the primer is located in the center of the
cartridge case head. Unlike rimfire
cartridges,
the primer is a separate and replaceable component. The centerfire
cartridge has replaced the rimfire in all but the smallest cartridge
sizes. Except for low-powered .22 and .17 HMR caliber cartridges, and
certain antique firearms, all modern pistols, rifles, and shotguns
used centerfire ammunition.
CHAIN
GUN:
a type of machine gun or autocannon that uses an external source of
power to cycle the weapon.
CHAMBER:
the portion of the barrel or firing cylinder where the cartridge is
inserted prior to being fired. It prevents expansion of the case as
the propellant ignites. Rifles and pistols generally have a single
chamber in their barrels, while revolvers have multiple chambers in
their cylinders and no chamber in their barrel.
CHAMBERING:
Inserting
a round into the chamber, either manually or through the action of
the weapon [IE, pump-action,
lever-action,
bolt-action,
or automatic-action].
CHARGER:
a
speedloader that
holds several cartridges together in a single unit for easier loading
of a firearm's magazine. A stripper clip is used only for loading the
magazine and is not necessary for the firearm to function.
CHOKE:
a
tapered constriction of a shotgun barrel's bore at the muzzle end.
Chokes are almost always used with modern hunting and target shotguns
to improve performance.
CLIP:
a
device that is used to store multiple rounds of ammunition together
as a unit, ready for insertion into the magazine
of
a repeating firearm. This speeds up the process of loading and
reloading the firearm as several rounds can be loaded at once. The
term clip
is
erroneously used to describe a firearm magazine because the clip
feeds ammunition to a magazine or revolving cylinder, while a
magazine or belt is used to load cartridges into the chamber of a
firearm ready for firing.
COLLATERAL
DAMAGE: Damage
that is unintended or incidental to the intended outcome. The term
originated and is used by US military personnel, but has expanded
into civilian terminology.
COLLIMATOR
SIGHT: a
type of optical “blind” sight
that
allows the user looking into it to see an illuminated aiming point
aligned with the device the sight is attached to no matter what
position of the eye [parallax
free].
The user can not see through the sight so it is used with both eyes
open while one looks into the sight, with one eye open and moving the
head to alternately see the sight and then at the target, or using
one eye to partially see the sight and target at the same time.
Another description often used is occluded
eye gunsight
[OEG].
COMBINATION
GUN: a
shoulder-held firearm that has two barrels; one rifle barrel and one
shotgun barrel. Most combination guns are over/under designs
[abbreviated as O/U] where two barrels are stacked vertically on top
of each other, but some combination guns are side-by-side in design
[abbreviated as SxS] – where two barrels are beside each other,
brazed
together.
CORDITE:
Smokeless
propellant that was developed and produced in the United Kingdom from
1889 to replace gunpowder as a military propellant. Cordite is
classified as a low explosive, like gunpowder, because it burns
slowly and has low brisance.
The hot gases produced by burning gunpowder or cordite generate
enough pressure to propel a bullet or shell to its target, but not
enough to destroy the barrel of the firearm.
CQC:
Close Quarters Combat or Close Quarters Battle [CQB] is a type of
fighting where small units engage the enemy with personal weapons at
short range, sometimes to the point of hand-to-hand combat or
fighting with hand weapons such as bayonets or knives.
CYLINDRO-CONOIDAL
BULLET: a
hollow base bullet that is shaped in a way that when fired, the
bullet expands and seals the bore. It was invented by Captain John
Norton
of
the British 34th
Regiment
in 1832, after he examined blow
pipe
arrows
used by natives in India and found their base was formed of elastic
locus pith, which by its expansion against the inner surface of the
blow pipe prevented the escape of air past it.
D
DAMASCUS
BARREL or
DAMASCUS
TWIST: an
obsolete method of manufacturing a firearm barrel made by twisting
strips of metal around a mandrel
and
forge welding it into shape.
DECOCKER:
Most
traditional double-action semiautomatic pistols are designed to be
carried with the hammer down [uncocked] on a chambered round, with or
without a manual safety engaged. A decocker or manual decocking lever
allows the hammer to be dropped on a live cartridge without risk of
discharging it, usually by blocking the hammer or retracting or
covering the firing pin before releasing the sear.
It eliminates the need to pull the trigger or to control the fall of
the hammer. Some systems are three-way, like Heckler
& Koch pistols. The Walther
PP and Beretta
92 use a two-way system, where engaging the safety also decocks
the firearm.
DERRINGER:
A
type of firearm usually designed with two barrels, side-by-side
or over-under, with a single frame.
DIRECT
IMPINGEMENT: a
type of gas
operation
for
a firearm that directs gas from a fired cartridge directly to the
bolt
carrier
or
slide
assembly
to
cycle the action.
DOGLOCK:
The lock that preceded the “true” flintlock rifles and pistols in
the 17th
century.
It was commonly used in Europe in the 1600s. It was popular with
British and Dutch military. A doglock carbine was the principle
weapon of the harquebusier,
the type most often used by the cavalry of armies of the Thirty
Years War and the
English Civil War eras.
DOUBLE-ACTION:
In semiautomatics, the double-action trigger mechanism is identical
to the double-action revolver; however, the firing mechanism
automatically cocks the hammer or striker after the gun is fired.
This mechanism will cock and release the hammer when the hammer is in
the down position, but on the next shot, the trigger will function as
a single action. The Beretta
Model 92 is a good example of a Double-Action/Single-Action
combination semiautomatic pistol. On many pistols, including the
Beretta, there is the option to cock the hammer before firing the
first shot. This removes the heavy pull of the double-action. Often
there is a decocker
to return the pistol to double-action. Double-action revolvers can be
fired in either mode by pulling the trigger or manually by cocking
the hammer [single-action]. For example, the Colt
Python
does not have to be fired in double-action mode.
DOUBLE-BARRELED
SHOTGUN: a
shotgun with two barrels, usually of the same gauge or bore. The two
types of double-barreled shotguns are over/under [O/U] where two
barrels are stacked on top of each other, and side-by-side [SxS]
where two barrels sit beside each other. Double-barreled firearms
that use one shotgun barrel and one rifle barrel is called
combination
gun.
DOUBLE
RIFLE: a
rifle that has two barrels, usually of the same caliber. The two
types of double rifles are over/under [O/U] where two barrels are
stacked on top of each other, and side-by-side [SxS], similarly to a
double-barreled shotgun.
DRILLING:
a
firearm with three barrels [German word drie
for
three] … typically it has two barrels side-by-side on the top, with
a third barrel underneath. It is primarily used for taking winged
animals as well as big game. It is also used in jurisdictions where a
person is only allowed to own a single firearm.
DRUM
MAGAZINE: a
type of firearm magazine that is shaped like a cylinder [drum].
DRY
FIRE:
the practice of “firing” a firearm without ammunition by pulling
the trigger and allowing the hammer
or
striker to
drop on an empty chamber.
DUM-DUM:
a
round of ammunition that is inert – no primer, no propellant, no
explosive charge. It is used for weapon function checks and for crew
training. Unlike a blank, it has no charge at all. [Also called a
dummy
round].
E
EJECTOR:
In a semi-automatic
rifle, pistol, or shotgun; it is a stationary pin that pushes
cartridge cases out of and away from the firearm during the recoil
process. In a revolver, the device often is a star shaped component
connected to the ejector rod
to assist in speedy cartridge removal.
EJECTOR
ROD: The rod used to
unload the cartridges and/or cases from a firearm.
ELECTRONIC
FIRING:
Using electric current to fire a cartridge instead of a percussion
cap. The electric current ignites the propellant and fires the
cartridge as soon as the trigger is pulled. CVA is one manufacturer
that produced electric firing muzzle loaders to reduce the time
loading and not requiring a primer cap to ignite the powder to propel
the ball/conical bullet down range. Electric trigger mechanisms are
also used in heavy caliber armed forces weapons, like the
20-millimeter “Vulcan”
M61
Cannon gatling
gun or other large
caliber gatling guns.
EYE
RELIEF: For
optics such as binoculars or a rifle scope, eye relief is the
distance from the eyepiece to the viewers eye which matches the
eyepiece exit pupil to the eye's entrance pupil. Short eye relief
requires the observer to press his or her eye close to the eyepiece
in order to see an unvignetted image. For a shooter, eye relief is
important and a safety concern. An optic with too short of an eye
relief can cause a skin cut at the contact point between the optic
and the eyebrow of the shooter due to recoil action.
EXPANDING
BULLET: a
bullet designed to expand on impact, increasing in diameter to limit
penetration and/or produce a larger diameter wound. The two typical
designs are the hollow point bullet and the soft point bullet. The
Hague Convention of 1899, Declaration III, prohibits the use of
expanding bullets in international warfare. The Geneva Convention,
contrary to belief, does not mention this restriction. Because the
Hague convention restriction only applies to war, expanding rounds
remain legal for civilian use, for example hunters use it to prevent
loss of a game animal and to ensure a humane death of vermin. Law
enforcement or civilians in self defense, use expanding bullets to
prevent collateral
damage
caused
by bullets passing through the aggressor and injuring innocent
people. [See Also: Frangible
and Stopping
Power]
EXTRACTOR:
a
part of a firearm that serves to remove brass cases of fired
ammunition after the ammunition has been fired. When the gun's action
cycles, the extractor lifts or removes the spent brass casing from
the firing chamber.
F
FALLING
BLOCK ACTION:
[also Sliding-Block
Action]
a single-shot firearm action in which a solid metal breechlock
slides
vertically in grooves cut into the breach of the rifle and actuated
by a lever. When in the top position, it is locked and resists the
force of recoil while sealing the chamber. In the lower position, it
leaves the chamber open to be loaded by a cartridge from the rear.
FERRITIC
NITROCARBURIZING:
A
case hardening process that diffuse nitrogen and carbon into ferrous
metals at sub-critical temperatures to improve scuffing resistance,
fatigue properties and corrosion resistance of metal surfaces. It is
also called nitriding.
FIRE
FORMING: The
process of reshaping a metallic cartridge case to fit a new chamber
by firing it within that chamber.
FIRING PIN: A
component forced into the primer of a cartridge by the force of the
hammer that results in a controlled explosion that launches the
projectile [bullet]. A spring driven firing pin on guns with no
hammer is used, such as for a Glock, and is called a Striker.
FLASH
SUPPRESSOR: An
accessory that attaches to the muzzle of a firearm and disperses the
ignited gases in order to restrain muzzle flash.
FORCING
CONE:
The tapered section at the rear of the barrel of a revolver that
eases the entry of the bullet into the bore.
FULL COCK: Refers
to the hammer fully retracted into firing position; a pistol ready
for firing.
FOULING
SHOT: a
shot fired through a clean bore, intended to leave some residue of
firing and prepare the bore for more consistent performance in
subsequent shots. The first shot through a clean bore will behave
differently then subsequent shots through a bore with traces of
powder residue, resulting in different point of impact. [See Fouling
Shot Journal, a publication of the Cast
Bullet Association].
FORWARD
ASSIST: a
button found on the M16 and AR-15 rifles, located near the bolt
closure where when hit will push the bolt carrier forward to ensure
the bolt is locked. Found in the earlier models, the more modern
models do not require to have a forward assist, as in Model M16-A1
and M16-A2 and AR-15s.
FOULING:
The
accumulation of unwanted material on solid surfaces. Fouling material
can consist of powder, lubrication residue, or bullet material such
as lead or copper.
FRANGIBLE:
a
bullet that is designed to disintegrate into tiny particles upon
impact to minimize their penetration for reasons of range safety, to
limit environmental impact, or to limit the danger behind the
potential target. Two examples are: Glaser
Safety Slug
and
a breaching
round.
FRIZZEN:
an
“L” shaped piece of steel hinged at the rear used in flintlock
firearms. The flint scraping the steel causes a shower of sparks to
be thrown into the flash pan.
G
GAS
CHECK: a
device used in some types of firearms ammunition when non-jacketed
bullets are
used in high
pressure cartridges.
GAS-OPERATED
RELOADING: a
system of operation used provide energy to operate autoloading
firearms.
GAUGE:
The gauge of a firearm is a unit of measurement used to express the
diameter of the barrel based upon the weight of the largest lead ball
the firearm can discharge. The only exception is the .410 shotgun
that refers to the actual diameter of the barrel.
GENERAL
PURPOSE MACHINE GUN: a
machine fun intended to fill the role of either a light machine gun
or medium machine gun, while at the same time being more portable.
GRAIN:
a
unit of measurement used in firearms to denote the amount of powder
in a cartridge or the weight of a bullet, as used in weighing grain
of wheat or barley, but since 1958, the grain [gr] measure has been
redefined using the International
System of Units as precisely 64.798 mg. There are 7,000 grains
per avoirdupois
pound
in the Imperial and US customary units.
GRIP
SAFETY: a
safety mechanism, usually a lever on the rear of a pistol grip, that
automatically unlocks the trigger mechanism of a firearm as pressure
is applied by the shooter's hand.
GROUPING/GROUP:
The
pattern of bullets fired at a target in succession without changing
the aiming point; often used to determine performance accuracy in
rapid fire circumstances and to adjust sighting.
GUNPOWDER:
also
called black
powder,
it is a mixture of sulfur, charcoal, and potassium
nitrate. It burns rapidly and produces a volume of hot gas made
up of carbon
dioxide, water [H2O]
and nitrogen, and
a solid residue of potassium
sulfide. Because of its burning properties
and
the amount of heat and gas volume that it generates, gunpowder is
widely used as a propellant in firearms and as a pyrotechnic
composition
in fireworks.
Modern firearms do not use traditional black powder, but instead uses
smokeless
powder.
H
HAIR
TRIGGER: A trigger that
requires a small amount of force to depress. Often used for target
practice or competition shooting, it provides a more consistent aim
and steady repeated shooting. Not recommended for combat or
self-defense or concealed-carry handguns.
HALF
COCK: A safety notch
built into the hammer where it clicks into place at the halfway
point. In single-action Old West handguns, it was intended to prevent
accidental dropping of the hammer.
HAMMER
BITE: The
action of an external hammer pinching or poking the web of the
operator's shooting hand between the thumb and fore-finger when the
gun is fired. Some handguns are prone to this like the M1911
and
Browning Hi-Power
pistols.
HAMMERLESS:
A
specific firearm design where the hammer or striker is integrated
into the firearm's interior.
J
JACKETED
BULLETS: [also
– full-metal
jacket bullet]
a bullet that has a soft core (usually lead) encased in a shell of
harder metal, like cupronickel
,
gliding
metal or
a steel alloy. A full-metal jacket extends completely around the
bullet. The jacket allows for higher muzzle velocities than bare lead
without depositing amounts of metal in the bore. It also prevents
damage to bores from steel or armor-piercing
core
materials. The FMJ [full-metal jacket] is easily recognized from
hollow-point or soft-point bullets. The first successful full-metal
jacket
rifle
bullets were invented by Lt. Col. Eduard
Rubin of
the Swiss Army in 1882. Full-metal jackets were first used
as
standard ammunition in 1886 for the French Mle
1886 Lebel
Rifle. Full-metal jacket bullets produce smaller entry wound
sizes than soft-tipped bullets and can be used against soft or hard
targets.
JAM:
A
generic term used when referring to any firearm malfunction that
involves failure of moving parts, faulty ammunition, poor
maintenance, or misuse.
JEWELING:
a cosmetic process to enhance the looks of firearm parts, such as the
bolt. The look is created with an abrasive brush and compound that
roughs the surface of the metal in a circular pattern.
K
KEYHOLE
or
KEYHOLING:
Refers to the shape of the hole left in paper target by a bullet
fired down a gun barrel which has a diameter larger than the bullet
or which fails to properly stabilize the bullet. A bullet fired in
this manner tends to wobble or tumble as it moves through the air and
leaves a “keyhole” shaped hole in a paper target instead of a
round one.
KYBER
PASS COPY: a
firearm manufactured by cottage gunsmiths in the Kyber Pass region
between Pakistan and Afghanistan.
L
LANDS:
In rifled barrels these are the treads or raised portions in
relation to the grooves.
LENGTH
OF PULL: The distance between
the trigger and the butt end of the stock of a rifle or shotgun.
LEVER-ACTION:
a type of firearm action which
uses a lever located around the trigger guard area, often including
the trigger guard itself, to load fresh cartridges into the chamber
of the barrel when the lever is worked.
LIGHT
MACHINE GUN: a machine gun
designed to be employed by an individual soldier.
LIVE
FIRE EXERCISE [LFX]: Any
exercise in which a realistic scenario for the use of specific
equipment is simulated. In the popular terminology this is applied
primarily to tests of weapons or weapon systems that are associated
with the various branches of a nation's armed forces, although the
term can be applied to the civilian arena as well.
LOCKED-BREACH:
[Also see Recoil]
A system designed for more powerful pistols like 9mm Parabellum and
.45 ACP needed to retard breech opening requiring a heavy slide and
stiff spring, which makes them bulkier than blowback design models.
In the classic locked-breech pistol, the barrel is locked to the
slide, but the slide is not locked to the frame [receiver]. Some have
tilting barrels with locking lugs on top of the barrel [1911, High
Power, and Neuhausen]; while others have a separate locking block to
connect barrel and slide like P-38, Lahti, and Beretta. Luger is
unique from the other two types in that is uses a toggle action that
is less commonly seen; however, all are locked-breech actions.
LOAD: A general
term that refers to all the component parts of a cartridge. It is
also the act of placing ammunition in the chamber of a firearm or the
amount of powder in a cartridge or hand-loaded blackpowder muzzle
loading firearm.
LUG:
Any piece that projects from a
firearm for the purpose of attaching something to it. For example,
barrel lugs are used to attack a break-action shotgun barrel to the
action itself. If the firearm is a revolver, the term may also refer
to a protrusion under the barrel that adds weight, thereby
stabilizing the gun during aiming, mitigating recoil, and reducing
muzzle flip.
A full lug extends all the way to the muzzle, while a half lug
extends partially down the barrel. ON a swing-out
cylinder revolver, the
lug is slotted to accommodate the ejector rod.
M
MACHINE
GUN: a fully automatic mounted
or portable firearm.
MACHINE
PISTOL: A handgun-style fully
automatic or burst-mode firearm.
MACHINE
REVOLVER: A revolver that uses
the energy of firing for cocking the hammer and revolving the
cylinder, rather than using manual operations to perform these
actions. A more correct term is semi-automatic
revolver.
MAGAZINE:
A magazine is an ammunition
storage and feeding device within or attached to a repeating firearm.
Magazines may be integral to the firearm [fixed] or removable
[detachable]. The magazine functions by moving the cartridges stored
in the magazine into a position where they may be loaded into the
chamber by the action of the firearm. Magazines are often mistakenly
called “clips” [by civilians] - which is an entirely different
mechanism.
MAINSPRING:
The spring
which drives the firing pin of a firearm. It is part of the action
assembly.
MATCH
GRADE: Firearm parts and
ammunition that are suitable for a competitive match. This refers to
parts that are designed and manufactured in such a way that they have
tight tolerances and a high level of accuracy.
MOA: {Minute of Angle) ... an angular measurement 1/60th of a degree. 1 MOA spreads about 1" per 100 yards. 1 MOA is different size at different distances - 8" spread at 800 yards. The following NSSF video explains MOA, important for long-range, scoped rifles used by military snipers, hunters, and competition long-range shooting.
MUZZLE: The part of a firearm at the end of the barrel from which the projectile will exit.
MUZZLE
BRAKES and RECOIL
COMPENSATORS: Devices that are
fitted to the muzzle of a firearm to redirect propellant gases with
the effect of countering both recoil and unwanted rising of the
barrel during rapid fire.
MUZZLE
ENERGY: The
kinetic
energy
of
a bullet as it is expelled from the muzzle of a firearm. It is often
used as a rough indication of the destructive potential of a given
firearm or load. The heavier the bullet and the faster it moves, the
higher its muzzle energy and the more damage it will do.
MUZZLE FLASH: The
brief, intense flaring of ignited, expanding gases that emerge from
the end of the barrel with the bullet, reacting with the oxygen in
the air when a firearm discharges.
MUZZLE
LOADER: Any
traditional firearm, pistol, rifle, or shotgun, that is loaded by
inserting a powder charge followed by a bullet, lead ball, or shot
projectiles through the muzzle. This type of firearm is also called
blackpowder firearms.
MUZZLE
VELOCITY: The
speed at which a projectile leaves the muzzle of a firearm. Muzzle
velocities range from approximately 800 ft/s (240 m/s) for some
pistols and older cartridges to more than 4,000 ft/s (1,200 m/s) in
modern cartridges such as the .220
Swift and .204
Ruger.
N
NECKING
DOWN or NECKING UP: refers to
shrinking or expanding the neck of an existing cartridge to make it
use a bullet of a different caliber. A typical process used in the
creation of wildcat
cartridges.
NOSE:
The forward
tip, usually a narrow point, of a bullet or other projectile.
NRA
[National
Rifle Association of America]:
an American organization which lists as its goals to protect the
Second
Amendment of the United States Bill
of Rights and the promotion of firearm ownership rights as well
as marksmanship, firearm
safety,
and the protection of hunting and self-defense in the United States.
The NRA is also the sanctioning body for most marksmanship
competition in the United States from the local level to the Olympic
level.
O
OBTURATE:
The process of a bullet
expanding under pressure to fit the bore of the firearm, or a
cartridge case expanding under pressure to seal the chamber. See also
swage.
OUT-OF-BATTERY:
The status of a weapon before
the action has returned to the normal firing position. The term
originates from artillery, referring to a gun that fires before it
has been pulled back into its firing position in a gun battery. In
firearms where there is an automatic loading mechanism, a condition
in which a live round is at least partially in the firing chamber and
capable of being fired, but is not properly secured by the usual
mechanism of that particular weapon can occur.
OVER-BORE:
Small caliber bullets being
used in very large cases. It is the relationship between the volume
of powder that can fit in a case and the diameter of the inside of
the barrel or bore.
OVER
AND UNDER: A
double-barrel firearm with two barrels arranged in a vertical
configuration, typically a shotgun.
P
PARKERIZING:
A method of protecting a steel
surface from corrosion and increasing its resistance to wear through
the application of an electrochemical phosphate conversion coating.
Also called phosphating
and phosphatizing.
PARTRIDGE SIGHT: A
type of handgun sight with a semi-rectangular shape.
PATTERN:
The
arrangement or spread of shot when fired from a shotgun. General
measurements are derived from the percentage of pellets that
terminate in a 30-inch target area 40 yards from the point of
discharge.
PERCUSSION
CAP: a small cylinder of copper
or brass that was the invention that enabled muzzle-loading firearms
to fire reliably in any weather. The cap has one closed end. Inside
the closed end is a small amount of a shock-sensitive explosive
material such as fulminate of mercury. The percussion cap is placed
over a hollow metal “nipple” at the rear end of the gun barrel.
Pulling the trigger releases a hammer which strikes the percussion
cap and ignites the explosive primer. The flame travels through the
hollow nipple to ignite the main powder charge.
PICATINNY
RAIL: A bracket used on some
firearms in order to provide a standardized mounting platform.
PINFIRE:
an obsolete type of brass
cartridge in which the priming compound is ignited by striking a
small pin which protrudes radially from just above the base of the
cartridge.
PLINKING:
informal target shooting done
at non-traditional targets such as tin cans, glass bottles, and
balloons filled with water.
POWERHEAD:
a specialized firearm used
underwater that is fired when in direct contact with the target.
[also called bang stick]
PRIMER:
Small
compartment of a cartridge containing a combustible material, which
when struck with the firing pin or striker, creates the spark that
ignites the gunpowder that propels the projectile from the barrel.
PUMP-ACTION:
a rifle or shotgun in which the
handgrip can be pumped back and forth in order to eject a spent round
of ammunition and to chamber a fresh one. It is much faster than a
bolt-action and somewhat faster than a lever-action, as it does not
require the trigger hand to be removed from the trigger while
reloading. When used in rifles, this action is commonly called a
slide action.
Q
QUAD-BARRELLED:
a
gun, usually artillery, with four barrels, such as the ZPU.
R
RAMROD:
a device used with early
firearms to push the projectile up against the propellant
[gunpowder].
RATE
OF FIRE: the frequency at which
a firearm can fire its projectiles.
RECEIVER: The
frame or action body portion of a firearm in which the firing
mechanism is contained. This part joins the barrel and the stock. It
is also called the frame in break-open firearms.
RECOIL:
The backward momentum of a
firearm when it is discharged. In technical terms, the recoil caused
by the firearm exactly balances the forward momentum of the
projectile, according to Newton's third law. [often called kickback
or kick]
RED
DOT SIGHT: a
type of reflector [reflex] sight for firearms that provides a red
light-emitting
diode as a reticle
to
create an aim
point
for
low-light conditions.
REFLECTOR
(REFLEX) SIGHT: a
non-magnifying optical device that has an optically
collimated
reticle,
allowing the user to look through a partially reflecting glass
element and see a parallax
free
cross hair or other projected aiming point superimposed on the field
of view.
It was invented in 1900 but was not popularly used on firearms until
more reliable versions were invented in the late 1970s. It is usually
referred to as a reflex
sight.
REVOLVER:
a repeating firearm that has a
cylinder containing multiple chambers and at least one barrel for
firing.
RIFLE
BEDDING: a process of filing
gaps between the action and the stock of a rifle with an epoxy based
material.
RIFLING:
Helical
grooves
in the barrel of a gun or firearm, which puts a spin to a bullet
around its long axis. This spin serves to gyroscopically
stabilize the bullet and improve its aerodynamic
stability and accuracy. Also refers to the process of machining the
grooves of a barrel.
RIMFIRE:
a type of firearm cartridge
that uses a firing pin which strike's the base's rim instead of
striking the primer cap at the center of the base of the cartridge to
ignite [centerfire
cartridge]. The rim of
the rimfire cartridge is an extended and widened percussion cap which
contains the priming compound, while the cartridge case itself
contains the propellant powder and projectile [bullet].
ROLLING
BLOCK: a form of firearm action
where the sealing of the breech is done with a circular shaped
breechlock able to rotate on a pin. The breechlock is locked into
place by the hammer, thus preventing the cartridge from moving
backwards at the moment of firing. By cocking the hammer, the
breechlock can be rotated freely to reload the weapon.
S
SABOT:
a
device used in a firearm to fire a projectile, such as a bullet, that
is smaller than the bore diameter.
SAFETY:
a
mechanism used to help prevent the accidental discharge of a firearm,
helping to ensure safer handling. Safeties can be divided into
subtypes such as internal safeties and external safeties. Sometimes
they are called “passive” and “active” safeties or
“automatic” and “manual”.
SAWED-OFF
SHOTGUN [SBS]:
a type of shotgun with a shorter barrel often a shorter or deleted
stock.
SEAR: The part of
a firearm [automatic and semi-automatic] that prevents more than one
shot from being fired at one time.
SELECTIVE
FIRE: a
firearm that fires semi-automatically and at least one automatic mode
by means of a selector depending on the weapon's design. Some
selective fire weapons use burst fire mechanisms to limit the maximum
or total number of sots fired automatically in this mode. The most
common limits are two or three rounds per pull of the trigger. The
M16A2 has a three-round burst mode.
SEMI-WADCUTTER
[SWC]:
a type of all-purpose bullet commonly used in revolvers which
combines features of the wadcutter
target
bullet and traditional round-nosed revolver bullets, and is used for
hunting, target shooting, and plinking. The design consists of a
conical nose, truncated with a flat point, sitting on a cylinder. The
flat nose punches a clean hole in the target and the sharp shoulder
enlarges the hole neatly, allowing easy and accurate scoring of the
target.
SHOTSHELL: A
complete round of shotgun ammunition consisting of multiple pellets
[shot], propellant, primer, and casing. Also known as a shotgun
shell.
SIGHT
RADIUS: The
distance between the front and rear sights. The longer the radius the
more accurate the sights will be.
SINGLE-ACTION
(SA): usually
refers to a pistol or revolver, single-action is when the hammer is
pulled back manually by the shooter (cocking it), after which the
trigger is operated to fire the shot. [see also double-action]
SLAMFIRE:
a
premature, unintended discharge of a firearm that occurs as a round
is being loaded into the chamber.
SLEEVING:
a
method of using new tubes to replace a worn-out barrel.
SLIDE: The part of
the action on a semi-automatic or automatic that moves back and forth
to eject an empty case and reload a loaded cartridge from the
magazine.
SLIDE
BITE: a
phenomenon that is often related to hammer
bite.
In this case the web of the shooting hand is cut or abraded by the
rearward motion of the semi-automatic pistol's slide, not by the
gun's hammer. It most often occurs with small pistols like the
Walther PPK
and Walther TPH
that have an abbreviated grip tang. This problem is caused most often
by sharp machining found on firearms.
SMOKELESS
POWDER: the
name given to propellants used in firearms and artillery that produce
a small amount of smoke when fired, unlike black
powder.
The term is generally not used in other English speaking countries
beyond the United States, adopting the term Cordite.
Smokeless powder allowed the development of modern semi-auto and
fully automatic firearms and lighter breeches and barrels for
artillery. It burns cleaner than black powder and thus is not apt to
foul moving parts. Smokeless powders are classified as division 1.3
explosives and is
regulated
by the US ATF. Various types of smokeless powder, including pellets,
has a nitro-based chemical that makes it burn cleaner. Muzzle-loading
rifles made after 1984 are designed to use smokeless powder loads
as well as sabot bullets instead of traditional lead balls. Muzzle
loaders are delighted because they need not worry as much about
corrosion as the traditional black powder causes. After every twenty
five shots, the breech plug is removed with a 5/8-inch socket wrench
and the barrel is cleaned out with a twenty gauge shotgun brass or
stainless steel brush and cleaned like any modern high-power rifle.
When cleaning with black powder, the barrel must be cleaned with a 20
gauge brass or stainless steel shotgun brush followed by a soap and
water bath. However, all powder
loads must be measured carefully to prevent too much stress on
the barrel. Except for custom barrels on other manufactured muzzle
loaders, Savage is the major source for out-of-the-box muzzle loaders
safe enough to use smokeless powder. Reenactment units often prefer
to use the old traditional black powder in their firearms because of
its “authentic” signature of smoke when fired. CVA
for example stresses that only black powder be used in their
firearms. Make sure your barrel can stand the stress of the smokeless
powder before using it.
SPEEDLOADER:
a device used for loading a firearm or firearm magazine with loose
ammunition quickly. Speedloaders are generally used for loading all
chambers of a revolver at once, although speedloaders of different
designs are also used for loading a fixed tubular magazine for a
shotgun or rifle, or the loading of box or drum magazines. Revolver
speedloaders are used for revolvers having either swing-out cylinders
or top-break cylinders.
SPORTERIZING:
The
practice of modifying military-type firearms either to make them
suitable for civilian sporting use or to make them legal under the
law.
SPUR:
The
projection on the hammer used to pull the hammer when cocking.
Sometimes refers to the machined area of a trigger, sear and other
action parts.
SQUIB
LOAD: a
firearms malfunction in which a fired projectile does not have enough
force behind it to exist the barrel, and thus becomes stuck.
STOCK:
The
part of a rifle or other firearm where the barrel and firing
mechanism are attached and held against one's shoulder when firing
the gun. The stock provides a means for the shooter to firmly support
the device and easily aim it.
STOPPING
POWER: The
ability of a firearm or other weapon to cause a penetrating ballistic
injury to a target, human, or animal sufficient to incapacitate the
target where it stands.
STRIPPER
CLIP: A
speedloader that holds several cartridges together in a single unit
for easier loading of a firearm's magazine. A stripper clip is used
only for loading the magazine and not necessary for the firearm to
function. Magazines are sometimes mistakenly referred to as “clips”.
SUPPRESSOR
[also
sound suppressor,
sound moderator,
silencer]:
a device attached to or part of the barrel of a firearm to reduce the
amount of noise and flash generated by firing the weapon. Suppressors
are restricted by the US federal government and can only be obtained,
used or manufactured with a special licensing/registration and the
suppressor must have a identification serial number stamped on its
surface.
SWAGE:
To
reduce an item in size by forcing through a die.
In internal ballistics, swaging refers to the process where bullets
are swaged into the rifling of the barrel by the force of the
expanding powder gases.
SWAGED
CHOKE: a
constriction or choke in a shotgun barrel formed by a swaging process
that compresses the outside of the barrel.
SWAGED
RIFLING: Rifling
in a firearm barrel formed by a swaging process, such as button
rifling.
T
TAYLOR
KO FACTOR: a
mathematical approach for evaluating the stopping
power of
hunting cartridges.
TELESCOPING
STOCK or COLLAPSING STOCK: a
stock on a firearm that telescopes or folds in on itself in order to
become more compact. Telescoping stocks are useful for storing a
rifle or weapon in a space that it would not normally fit.
TERMINAL
BALLISTICS: a
sub-field of ballistics – the study of the behavior of a projectile
when it hits its target.
TRIGGER LOCK: A
safety accessory that inhibits depression of the trigger. These are
recommended for use with unloaded firearms because removing the lock
may apply enough force to the trigger where accidental discharge will
occur.
TRIGGER
PULL: The
amount of force required to fully depress the trigger of a firearm
that is expressed in pounds. This force can vary, depending upon
firearm type, with target firearms requiring only about one pound
pressure and double-action firearms requiring about 15 pounds.
TRUNNION:
a
cylindrical protrusion used as a mounting and/or pivoting point. On
firearms, the barrel is sometimes mounted on a trunnion, which in
turn is mounted to the receiver.
U
UPSET
FORGING: a
process that increases the diameter of a workpiece by compressing its
length.
UNDERLUG:
(1)
locking lugs on a break-action firearm that extend from the bottom of
the barrels under the chamber(s) and connect into the receiver
bottom. (2) the metal shroud underneath the barrel of a revolver that
surrounds and protects the extractor rod. The two types of underlugs
include half-lug and full-lug [full-length of barrel].
V
VARMINT
RIFLE: a
small-caliber rifle or high-powered air gun primarily used for
varmint hunting – killing non-native or non-game animals such as
rats, house sparrows, starling, crows, ground squirrels, gophers,
jackrabbits, marmots, groundhogs, porcupine, opossum, coyote, skunks,
weasels, or feral cats, dogs, goats, pigs and other animals
considered to be nuisance vermin destructive to native or domestic
plants and animals.
VELOCITY:
The
rapidity or speed of a projectile. The standard unit is feet per
second. [F/S]
W
WADCUTTER:
a
special-purpose bullet designed for shooting paper targets, usually
at close range and at subsonic velocities, usually under 800 ft/s
(240 m/s). Often used in handguns and airgun competitions. A
wadcutter has a flat or nearly flat front that cuts a clean hole in
paper targets making it easier to score and in favor of the shooter.
WHEELLOCK:
an
obsolete mechanism for firing a firearm.
WILDCAT
CARTRIDGE: a
custom cartridge which ammunition and firearms are not mass-produced.
The cartridges are often created in order to optimize certain
performance characteristics (power, size, or efficiency) of an
existing commercial cartridge. [see improved
cartridge]
WINDAGE:
The
side-to-side adjustment of a sight, used to change the horizontal
component of the aiming point. (see Kentucky
windage)
X
X-RING:
a
circle in the middle of a shooting target bullseye used to determine
winners in event of a tie.
Y
YAW:
The
heading of a bullet, used in external
ballistics
that
refers to how the Magnus
effect
causes
the bullet to move out of a straight line based on their spin.
Z
ZERO-IN
or ZEROING: The
act of setting up a telescopic or other sighting system so that the
point of impact of a bullet matches the sights at a specified
distance.