Firearms Glossary
Your ultimate guide for common firearm termsWelcome to the Gunbuyer firearms glossary. Gunbuyer is committed to helping our customers, including those new to firearms, find the correct firearms, ammunition, and accessories for their particular needs. We understand that the names and terms used to describe the products we sell can be confusing to someone new to the firearms world. That's why we have created this firearms glossary. Here you will find explanations to the terms most often used to describe the products listed on this website. By using this glossary, it is our hope that you are better able to find exactly the right products and accessories for your individual needs.
A
Action
The physical mechanism that seals the breech and/or manipulates cartridges. The term explains the method in which cartridges of ammunition are loaded, locked, and extracted from that mechanism. Some examples would be: Single Action, Double Action, SA/DA, Double Action Only, etc.
AK
When used as abbreviated above, it generally refers to an AK-47. AK-47 stands for the Avtomat Kalashnikova which is a gas operated 7.62x39mm rifle developed in the Soviet Union by Mikhail Kalashnikov in 1947.
Ammunition / Ammo
The assembly of a projectile and it’s propellant in a single package.
AR
Many people believe that “AR” stands for “automatic rifle” – and this would be incorrect. AR originally stood for “Armalite Rifle” and most commonly refers to an AR-15 style rifle when the term is used.
Automatic Rifle
A self-loading rifle that is capable of automatic fire – where the firearm chambers, fires, and ejects multiple cartridges with a single trigger pull. Also referred to as a “machine gun.” These firearms are strictly regulated under the National Firearms Act (NFA).
B
Ballistics
The science and examination of a projectile’s path, behavior and effects once a bullet leaves its casing.
Barrel
A tube, most commonly metal, through which a controlled explosion or rapid expansion of gasses are released to propel a projectile out the end of the tube (or barrel) at high velocity.
Birdshot
A type of shotgun shell that is made for hunting birds and waterfowl. Specifically, it is the smallest load for a shotgun comprised of small shot – typically made of lead or steel.
Blank
A type of firearm cartridge that contains gunpowder, but no bullet or shot. When fired, the blank makes a flash and a loud report. Commonly used for the start of races, movies and special effects, reenactments, and training.
Bluing
A preservation process where steel is partially protected against rust. It is named for the resulting blue-black finish.
Bolt Action
A type of firearm action where the firearm’s bolt is manually operated by a small handle to open and close the breech. As the handle is operated, the bolt is unlocked, the breech is opened, the spent shell casing is withdrawn and ejected, the firing pin is cocked, and a new round (if present) is placed into the breech and the bolt is closed.
Bore
The interior of a firearm barrel. The diameter of the bore is considered the caliber, which is the outside diameter of the ammunition used in the firearm.
Bore Sight
The act of aligning the bore axis with a target then adjusting the sights be they open sights or some type of optic to match the same position on the target as the bore axis. This can be done by the naked eye or with a laser and normally saves time when sighting in a new sight.
Buckshot
A type of shotgun cartridge, named for its intended use in hunting medium game (such as Buck deer). It is also commonly used by Law Enforcement, Military, and for civilian self defense purposes. It is comprised of fewer shot, but larger diameter than birdshot.
Bullet
The portion of an ammunition cartridge that is the projectile which is fired from the barrel of a firearm, typically cylindrical and pointed.
Bullpup
A firearm configuration where the magazine and action are both located behind the trigger. Bullpup firearms allow for standard length barrels to be used in compact packages for easier transport and use in narrow environments where space is a premium.
C
Casing
The container portion of an ammunition cartridge that contains the gunpowder, projectile, and primer. Casings are generally metal, most commonly from brass, steel, and aluminum. Shotgun casings are made of plastic.
Caliber
The diameter of the inside of the firearm’s barrel determines which ammunition that gun can fire. Examples would be: .45 (fractions of inches) or 9mm (in millimeters).
Carbine / Ammo
A shortened version of a service rifle, generally made for use by cavalry. In modern day the carbine does not have a fixed stock but instead has a variable position stock to make it compact when in storage or close quarters but allows for longer more traditional stock lengths when extended.
Cartridge
A full assembly consisting of a bullet, gunpowder, shell casing, and primer. When counting It is typically referred to as a “round.”
Chamber
The portion of the firearm in which the cartridge is inserted prior to being fired. Rifles and pistols have a single chamber, revolvers have multiple chambers in their cylinders and no chamber in their barrel.
Choke
A tapered construction of a shotgun barrel’s bore at the muzzle end. Chokes are generally used in hunting and target applications to improve performance.
Clip
Often used incorrectly in place of magazines. A clip holds cartridges together and is used to either reload magazines (stripper clip) or is inserted into the firearm directly (en-bloc clip). A magazine has an entirely different and more complicated construction. Revolvers use “Moon Clips” and “Half-Moon Clips” which are cut metal pieces designed to hold a full cylinder or half a cylinder’s worth of ammunition, respectively – quickly into the revolvers cylinder.
Cock
Manually drawing back the hammer of a gun against its spring, which then arms the hammer to release once the trigger is pulled.
Concealed Carry
Concealed carry refers to the ability to conceal a weapon of choice be it a firearm, knife, taser, and or pepper spray. You may also need a license to carry in certain states which is known as a CCP or CWP license.
Cylinder
Found in revolvers, this is the portion of the firearm that contains multiple chambers. The cylinder rotates, aligning the chamber with the barrel.
Charging Handle
Device on a firearm that, when operated, results in the hammer or striker being cocked or moved into the ready position.
D
Decibel
Decibels refer to the measure of sound levels. Sound is measured through the use of db units(decibels). The higher the decibel rating, the louder the noise, and conversely the lower the decibels, the lower the noise.
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.
Discharge / Ammo
To fire a weapon. A term used to describe the effect of the firing pin striking the primer causing the bullet to be expelled from the muzzle of the firearm.
Double Action (DA)
Refers to a long trigger pull that both cocks and releases the hammer to fire either a revolver or a pistol. The hammer may also be cocked manually, which then allows for a short trigger pull to fire the weapon.
Double-Barreled Shotgun
A shotgun with two barrels, usually of the same gauge or bore. The two configurations of a double barreled shotgun are over/under (O/U) and side by side (SXS or S/S).
Double Stack
A larger semi-automatic magazine that holds cartridges in 2 vertical lines, staggered side by side, with a tapered top that allows only one cartridge to be fed into the chamber of the firearm at a time.
Double Tap
A term used to define a shooting style usually used in defensive situations where two shots are fired in rapid succession to neutralize a threat.
Dummy Round
A device used for training purposes and to check weapon functionality. Dummy rounds are offered in a variety of calibers allowing the user to practice with the firearm of their choice in the comfort of their own home.
E
Elevation
A method of height adjustment, used in conjunction with windage, that allows the user to precisely move a reticle in line with the trajectory of a bullet. Usually by increments of ¼ MOA.
Extractor
The part in a firearm that serves to remove spent ammunition cases from the chamber.
Eye Relief
The distance from an optic to your eye where you are capable of viewing a full and clear picture. This will be different for each individual person.
F
Fiber Optic Sights
An optical fiber that collects and centers light along its fibers allowing the user to have a bright clear sight. These sights are usually made of thin strips (hair width) of either glass or plastic.
Field Strip
A term used for the disassembly of a firearm for general maintenance and repair. Normally, this does not require the use of tools on behalf of the user though they may be needed for further disassembly.
Firearm
A mechanical device designed to expel a bullet from an ammunition cartridge. A firearm is a general term used to describe different types and variants to include: rifles, shotguns, handguns and revolvers or anything else that falls under one of these categories.
Firing Pin
The part of a firearm that strikes the primer, discharging the weapon. Firing pins are pieces of metal, generally of a high grade, that can withstand the extreme temperature of the firing process.
Flash Suppressor
A device that is attached to the muzzle of a firearm, that lowers the temperature or disbursement of the gasses upon firing. These are primarily used to prevent the user from being blinded by the flash in low light situations or to conceal one's position during combat operations.
Focal Plane (1st & 2nd)
This has all to do with reticles and magnification. In 1st focal plane optics the reticle will grow and shrink as magnification is adjusted. 2nd focal plane optics will not have a reticle size change as magnification is changed.
FPS
Feet per second (FPS) is a measurement of velocity of the object as it travels through the air toward the target. Velocity will vary depending on bullet weight, trajectory, length of barrel, faster or slower burning propellant.
Forward Assist
A mechanical button, commonly found on AR style firearms, that allows the user to fully engage the bolt and seat the round in its proper position.
Fouling
The accumulation of unwanted material on solid surfaces. The fouling material can consist of either powder, lubrication residue, or bullet material such as lead or copper.
G
Grain
A unit of measurement used in the manufacturing of ammunition that describes the mass of bullets and powder.
Gun Trust
Gun trust refers to an official document that allows the trustees to acquire as well as, possess, ship, transport, receive, deliver, and transfer regulated firearms that are generally Title II NFA items.
Gunpowder
The component of ammunition that is used as a propellant in firearms. In modern day this is normally smokeless but black powder is still available and used in some firearms.
Gunsmith
Gunsmith refers to an individual who is certified to make legal alterations or modifications to firearms without the user risking injury. Gunsmiths can modify parts of the firearm to allow for better function for the end user.
H
Hair Trigger
A term used to describe the weight of a trigger in reference to being lighter than factory settings. Some triggers have an adjustability setting that allows the weight to be decreased meeting the requirements of the user.
Hammer
A mechanical piece of a firearm that contacts the firing pin (which in turn impacts that cartridge primer, causing the gun to be fired). There are different types of hammers to include: external, internal, bobbed, or shrouded.
Hang fire
An unexpected and abnormal delay between pulling the trigger of a firearm and the ignition of the propellant. This can be caused by faulty primers, light strikes of the firing pin or other cartridge related problems.
Holographic Sight
A specific type of red dot sight that uses lasers and mirrors to project a reticle. Their reticle will stay at the set MOA when magnified, remain in focus even when looking past the reticle and will continue to work even if the front glass is broken.
Hollow Point
A type of bullet designed to increase expansion upon penetration of its target. A hollow point has a concave nose, and occasionally material placed inside of the concave to assist in maximizing expansion. It generally does more internal damage to a target and is less likely to go completely through a target.
I
Iron Sights
Iron sights are typically composed of two component sights, formed by metal blades: a rear sight mounted perpendicular to the line of sight and consisting of some form of notch (open sight) or aperture (closed sight); and a front sight that is a post, bead, or ring..
IWB Holster
A holster that sits inside the waistband of a set of pants, usually used for concealed carry purposes. Can be made of leather, kydex or synthetic materials and usually has adjustment for height and cant angle.
J
Jam
A type of firearm malfunction where the bullet does not load or chamber properly and gets stuck.
JHP
Stands for “Jacketed Hollow Point.” Refers to a full cartridge containing a hollow point lead bullet wrapped in a jacket of copper. Generally selected for self-defense or hunting of game where you do not need much penetration.
K
Kick
A term used to describe the force of the perceived recoil or rearward momentum of a firearms action when it is discharged. Kick is used as a slang term to describe the recoil impulse of a firearms operation.
Kydex
Thermoplastic acrylic-polyvinyl chloride whose construction gives the plastic rigidity while also allowing it to be molded into various shapes. This allows for custom and firearm specific holsters that are extremely durable.
L
Length of Pull
The distance between the trigger and the rear end of the stock of a rifle or a shotgun. The length of pull is important because it allows the gun to fit the user properly so that they may shoot it correctly.
Lever Action
A type of firearm action with a lever that encircles 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.
M
Machine Gun
A fully automatic weapon capable of sustained fire without the reset of the trigger. These can be rifles, pistols or shotguns and require a tax stamp under the NFA. Per the NFA individuals can only possess machine guns manufactured prior to 1986.
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.
Magnum
A term used to describe a cartridge with a higher-velocity load or heavier projectile when compared to a standard cartridge of the same diameter.
MIlradian
A unit of measure that can be used to define shot groupings for use in rifle scope reticles.
Misfire
Used to describe when the primer in a cartridge fails to ignite, and thus the bullet does not fire.
MOA
Minute of Angle(MOA) is a measurement of the point of impact of the bullet on a target. The bullet will hit within the circle of impact which is referred to as MOA. For example 1 MOA equals 1” at 100 yards.
MSR
An abbreviation that stands for “Modern Sporting Rifle.” Modern Sporting Rifle refers to modern style rifles with characteristics outside the norm of sporting to include AR and AK pattern rifles and pistols as well as more technologically advanced designs.
Muzzle
A term for the end of the gun’s barrel where the projectile exits the barrel of the firearm.
Muzzle Velocity
The speed at which a projectile leaves the muzzle of a firearm. Normally measured in FPS.
N
Neck
The portion of the ammunition cartridge that grips the bullet.
NFA
NFA or National Firearms Act is a law that was founded by Congress to regulate the possession, sale, transfer, ownership, of certain firearms and accessories. These types of firearms and accessories are classified as Title 2 or Class 3 which are considered a SBR (Short Barreled Rifle), SBS (Short Barreled Shotgun), Suppressor, AOW (Any other Weapon) that require a tax stamp of either $200 or $5 depending on the item.
O
Open Carry
Carrying a firearm or weapon that is not concealed.
OWB Holster
A holster that sits outside the waistband of a pair of pants. Usually for duty use or competition but can also be used for hiking and hunting when dangerous game is present. Can be made from a variety of materials.
P
Picatinny Rail
A bracket used on firearms to provide a standardized mounting platform.
Pistol
A type of firearm that can be held and fired with one hand. The word pistol is usually used to refer specifically to a semi-automatic pistol.
Pistol Grip
A grip on a rifle or shotgun that resembles the grip normally associated with a pistol. These are most common and prevalent on AR style pistols and rifles and AK style pistols and rifles.
Plinking
Plinking is a term referencing casually shooting at targets on a shooting range. Plinking is used to describe a shooting style often associated with low caliber ammunition to include the 22LR.
Point Blank
Point blank refers to shooting an object up close where the use of sights are negligible. The user is literally pointing the gun and shooting at a close range target.
Pump Action
A repeating firearm where the action is worked by the sliding of a mechanism to both eject and load another round. This action works in line with the barrel of the firearm.
Q
N/A
R
Recoil
The rearward movement of the firearm resulting from the ignition of the propellant in the cartridge due to Newton's 3rd law of motion.
Red Dot Sight
Red Dot Sight refers to a sighting system used in handguns, rifles, and shotguns. Red Dot Sights utilize a red dot projected on a glass or polymer lens that is used in place of a traditional sighting system like iron sights.
Reflector (Reflex) Sight
A type of red dot sight in which a red dot is projected from the back of the sight and reflected off the front lens to the eye.
Revolver
Revolvers are a type of firearm that utilizes a revolving cylinder to fire off a succession of shots which are typically between 5-10 depending on the firearm.
Rifle
A shoulder fired weapon with a rifled barrel. Usually used for longer range shooting.
Rifling
Rifling refers to the spiral grooves in the barrel of the firearm. The lands and grooves allow the bullet to rotate. Rifling is used to describe the types of barrels to include 1:9 twist which means the bullet makes 1 revolution for every 9 inches.
Round
A singular cartridge consisting of the bullet, powder, primer and casing. These can be in a variety of calibers from .17 to over .50 cal.
RPM
Rounds Per Minute(RPM) is a term to describe the rate of fire associated with a type of firearm. Rounds Per Minute is commonly used to describe fully automatic firearms to analyze the rounds expelled in a certain amount of time.
S
Safety
A mechanism that prevents the firearm from discharging and protects the shooter. These can be internal, manual or integrated into the trigger or backstrap.
Saturday Night Special
Saturday night special is a pejorative term used to describe a type of firearm. The term is used as a derogatory label to identify certain firearms that are lower quality and are commonly used in crimes.
Sawed-off shotgun
A shotgun that typically has a barrel shorter than 18 inches and/or an overall length of less than 26 inches. These are considered regulated items under the NFA.
SBR
Short Barreled Rifle (SBR) is a term used by the ATF to describe certain types of rifles that have a barrel length below 16” and includes a stock. SBR’s are regulated under the NFA and are subject to a $200 tax stamp to possess and own.
Scope
A telescopic sight that allows for magnification to help the shooter identify their target. These can be clear glass, night vision, or thermal and can be used for hunting, target shooting or tactical purposes.
Semi-automatic
Semi Automatic is a term used to describe a type of firearm mechanism. Semi-auto firearms are referred to as firearms that fire with one pull of the trigger only. Once the trigger is pulled and the bullet has left the barrel, the user must release the trigger to reset the mechanism. Once reset, they can now fire the weapon again.
Shells
Shells, often referred to as shot shells, are ammunition used in shotguns. Shells or shotshells are made up of a shell casing that is plastic and is mounted to a brass base that contains a primer. Shot shells are loaded with shot or BB’s that contain wadding to hold them in the shell. Shells are measured by their gauge.
Shotgun
A shoulder fired weapon usually with a long barrel that fires small BBs or shot. The barrels are usually smooth bore meaning no rifling and can be used for a number of applications. They do not have a very far effective range.
Silencer
Silencer is a term used to describe a device that muffles the sound signature of a firearm to safe hearing levels. Silencers attach to the muzzle device of a firearm, and with proper ammunition(subsonic) will decrease the sound signature enough so the individual doesn't have to wear hearing protection.
Single Action
A firearm, usually a pistol, that needs to be cocked by hand before it can be fired.
Single Shot
Single Shot refers to the action of a type of firearm. Single shot firearms only fire one round before reloading. Single shot firearms are commonly used in hunting, and or target practice with newer shooters to learn the basics of gun safety.
Smokeless Powder
Any of a class of explosive propellants that produce comparatively little smoke on explosion and consist mostly of gelatinized nitrocellulose. Used in most modern ammunition.
Snub-nosed Revolver / Snubby
Snub-nosed revolver is a term used to define a type of revolver that has a barrel length of 3” or less. Some revolvers are designed with a shorter barrel and bobbed hammer for concealed carry.
Speed loader
A device that reduces the amount of time that needs to be spent when reloading a weapon. These can be configured to match the size and number of cartridges for specific revolvers.
Sporterizing
Sporterizing is a term used to describe the modification to a firearm to classify it as a sporting model from its current configuration. Mostly used in converting military style firearms to be more suited for civilian sporting use and to make them legal in certain jurisdictions.
Squib Load
A firearm malfunction when a round is fired but does not have enough propellant and the bullet does not exit the muzzle causing it to be stuck in the barrel.
Straw Purchase
Straw Purchase is a term used to describe the act of purchasing a gun for an individual that is not allowed to purchase firearms I.E. convicted felons. Straw purchases are when a person who is able to buy a firearm legally runs across an individual who cannot, the one who cant purchase firearms has the legal purchaser buy the firearm for him, and pays them for the transaction.
Stripper Clip
A type of speed loader that holds several cartridges in line making it easier to load into a magazine. This is popular for the military as it cuts down on the amount of time reloading compared to hand loading individual cartridges.
Suppressor
Suppressor is a term used to describe a device that muffles the sound signature of a firearm to safe hearing levels. Suppressors attach to the muzzle device of a firearm, and with proper ammunition(subsonic) will decrease the sound signature enough so the individual doesn't have to wear hearing protection.
T
Tax Stamp
A federal stamp issued under the National Firearms Act to purchase restricted firearms and accessories such as SBRs, SBSs, AOWs, suppressors and fully automatic firearms. Possession of the stamp is proof that the required tax has been paid and the purchaser can now legally possess the item.
Tracers
Tracer rounds are a type of ammunition that allows the user to see the projectile as it is being fired. Tracers are designed with a pyrotechnic charge located in the base. Once the round is fired, it ignites the charge and makes the bullet visible as it leaves the barrel and heads down range.
Trajectory
The path that the projectile takes from being fired to reaching its target.
Trigger
Trigger is the part of the firearm that when depressed, causes the firearm fire. The trigger is essentially a lever that actuates the mechanism in the firearm and allows it to be fired.
Tritium Sights
Iron sights embedded with tritium which, through its radioactive decay, causes phosphor to glow providing long lasting, non battery powered sights visible in low or no light situations. These sights will gradually dim and eventually need to be replaced.
U
N/A
V
N/A
W
Wadcutter
Wadcutter is a type of ammunition that is designed to cut nice/neat holes in paper targets. A wadcutter is a special purpose flat bullet that creates tight holes in paper targets for measuring. They are also often used in snub nosed revolvers for self defence due to the lack of muzzle velocity, the flat nose improves the lethality of the cartridge.
Waiting Period
Requirement by state law in which a person must wait a specified length of time before they can take possession of a firearm. This period of time is often referred to as a cooldown period to allow the purchaser time to reflect on their decision.
Windage
Windage is a term used to adjust the sighting picture for firearms. Windage refers to the horizontal axis of measuring the proper sight alignment. Windage allows the shooter to adjust their point of aim if they are either shooting a little to the left or right.
X
N/A
Y
N/A
Z
N/A