You need to use the right terminology if you want to hit the mark

accidental discharge: Also, negligent discharge. The act of firing the gun unintentionally. This occurs when the gun is improperly handled. This includes failing to properly clear the weapon.

ACP: Abbreviation for automatic Colt pistol. This is a caliber designation that refers to the headspace of the round.

action: A term used to describe how the firearm is operated or the operations of a trigger.

action, automatic: Any firearm that performs the tasks of extracting, ejecting, and loading of ammunition without any work required by the shooter. This class of weapons is further broken down by the ability, or inability, to fire multiple rounds with one pull of the trigger.

The term automatic is commonly used to describe fully automatic weapons. As such, always use semi-automatic to describe firearms that can’t fire multiple rounds with one trigger pull.

action, automatic, full: Full-auto weapons that are capable of continuous fire as long as the trigger is fully depressed.

action, automatic, semi: Semi-auto firearms that require the trigger to be pulled for each round fired.

action, bolt: A type of rifle where the bolt is manually operated by an attached handle. Working the bolt to the rear extracts and ejects a spent casing. As the bolt is worked forward, a fresh cartridge is placed into the chamber, and the trigger is reset.

action, break: A type of firearm where the chamber(s) is/are accessed by releasing the barrel or chamber assembly to hinge downward, allowing the shooter to eject spent casings and load fresh cartridges.

action, double (pistol): A term used to describe actions performed by the pistol’s trigger. Double-action triggers draw back the hammer or striker (the first action) and release it (the second action). Firing the pistol.

 action, double/single (pistol): A type of trigger that acts as a double-action trigger for the first shot in semi-automatic pistols. When the first shot is fired, the weapon cycles and re-cocks the hammer or striker. The trigger is now in single-action mode for all subsequent shots until the hammer is de-cocked.

action, lever: A type of rifle, pistol, or shotgun where the bolt is manipulated by a lever, usually found on the underside of the gun. As the lever is pushed away, spent casings are extracted and ejected. When the lever is returned, a fresh cartridge is loaded, and the trigger is reset.

action, pump: A type of rifle or shotgun where the bolt is manipulated by a sliding fore grip. As the fore grip is drawn back, the spent cartridge is extracted and ejected. When the fore grip is sent forward, a fresh cartridge is loaded into the chamber.

action, single (pistol): Any semi-automatic pistol or revolver where the trigger performs the sole task of releasing the hammer or striker. In the case of revolvers, the hammer must be cocked each time by the operator. 

ammunition: A combination of propellant and projectile combined in a single package or cartridge.

ammunition, subsonic: Ammunition designed to propel a bullet at a velocity slower than the speed of sound.

arquebus: An early musket with a hook or lug on the fore-end of the gun. The hook was used in conjunction with wall fortifications or a fork rest.

AR rifle: An ArmaLite rifle, originally designed by Eugene Stoner and sold to Colt Firearms company. M16 variants, M4 variants, and rifles using the Stoner design are all considered ARs.

assault rifle: A poorly defined political term generally meaning a magazine fed, automatically operated rifle capable of semi-automatic, burst, and/or automatic fire. Rate of fire is determined by a selector lever or switch. This definition may change between jurisdictions. 

backup iron sights (BUIS): A set consisting of front and rear sights that can be mounted on a rifle. Sights of this nature are installed as a backup to optical systems that may fail when their batteries run out.

ball ammunition: See bullet, full metal jacket.

ballistics: The study of projectile behavior from launch to impact with a target. When applied to firearms, there are four distinct fields of study. They are listed in chronological order below.

ballistics, external: The study of projectile behavior while in flight.

ballistics, internal: The study of projectile behavior while it’s in the barrel of a firearm.

ballistics, terminal: The study of projectile behavior as it impacts a target.

ballistics, transitional: The study of projectile behavior from the point when it leaves the barrel to the point when pressures from expanding gas from the propellant no longer influence its flight.

barrel: The part of a firearm that contains expanding gas from the propellant as it drives the projectile forward at high velocity.

battery, in: The condition of the firearm where the bolt or slide is fully forward and locked. Firearms in battery can be fired. Firearms not in battery can’t be fired.

birdshot: A class of shotgun ammunition consisting of tiny balls or pellets ranging in size from .08 to .22 inches.

blank: A cartridge consisting only of primer and propellant.

bolt: The part of a firearm designed to seal the breech during firing. The bolt generally houses the firing pin and extractor. Some firearms incorporate the ejector as part of the bolt.

bore: The interior of the gun barrel.

brass: A common term for an expended shell casing.

breech: The part of the barrel open for the loading of ammunition.

buckshot: A class of shotgun ammunition consisting of metal balls ranging in size from .24 to .39 inches.  

bullet, armor-piercing: A projectile with a hardened metal core encased in a softer jacket.

bullet, dum-dum: A bullet designed for maximum expansion on impact with a target. This term is archaic and seldom used in the modern era.

bullet, frangible: A bullet designed to disintegrate when it hits a hardened target.

bullet, full metal jacket: A soft core, usually lead, projectile fully encased in a harder metal jacket. This jacket prevents deformation of the bullet during the loading process and allows for higher muzzle velocity. Bullets of this type are known to overpenetrate or pass through a target. Also known as ball ammunition. Commonly abbreviated as FMJ.

bullet, hollow-point: A projectile with an exposed cavity at the nose. Projectiles of this type are designed for maximum expansion to cause increased damage and decrease the possibility of over penetration.

bullet, semi-jacketed: A projectile in which the metal jacket does not fully encapsulate the core.

bullet, wadcutter: A projectile specifically designed to shoot paper targets.

BUIS: Backup iron sights. A sighting system that is used when an optic fails.

bullpup: A rifle design in which the trigger is located in front of the ejection port. Rifles with this design can have a longer barrel and a shorter overall length.

burst: A string of shots fired from a fully automatic weapon. Example: a six- to nine-round burst. Firing in this manner gives the shooter greater control over recoil and helps with barrel temperature management. 

burst mode: A select fire option in some automatic weapons that fires a set number of rounds with a single pull of the trigger.

butt: The back of a rifle’s stock that rests against the shoulder. Also, the bottom of a pistol’s grip. 

caplock: Also, percussion lock. A lock mechanism for firing a musket.

caliber: The dimensions of a bullet and cartridge. The numerical portion is expressed in imperial units as hundredths of an inch, and in metric as millimeters. Secondary information describes the dimensions of the firearm’s chamber or bore, which the round can safely be fired from/through. Examples: .45 ACP, .357 Magnum, .30-06 Springfield.

carbine: A shorter-barreled version of a standard rifle.

cartridge: An entire assembly of projectile, primer, and propellant. Musket cartridges were made of paper and only contained projectile and propellant.

cartridge, centerfire:A cartridge of ammunition with its primer in the center of the base of the casing.

cartridge, magnum: A cartridge designed with more propellant and a heavier projectile than a cartridge of similar caliber.

cartridge, paper: A form of ammunition used with muzzle-loading muskets. The paper cartridge held enough powder and shot for a single firing round.

cartridge, paper, integrated: A form of ammunition used with early breech-loading firearms. The integrated paper cartridge held the primer, propellant, and projectile(s).

cartridge, pinfire: An early form of integrated metallic cartridge that contained the firing pin. 

cartridge, rimfire: A cartridge with its primer contained in the rim of the casing.

case/casing: The part of the cartridge that houses the propellant, primer, and projectile.

chamber: The part of a barrel designed to fit a specific cartridge. Revolvers and some shotguns have multiple chambers.

charging handle: A device used to manipulate the bolt. In automatic weapons it’s used to manually cycle the action.

choke: A device mounted inside the barrel of a shotgun, designed to alter the distribution of shot as it leaves the muzzle.

clear: (v.) The unloading of a firearm. (adj.) unloaded.

clip: A metal strip designed to hold cartridges by the rim until they are ready to be loaded into a magazine.

cock: The act of drawing back the hammer to a firing position. In muskets, the portion of the lock that holds a slow match or flint.

cylinder: A device that contains multiple chambers. This can be revolved manually or mechanically depending on the model of revolver. 

derringer: A small pistol with one or more barrels; designed to be a concealed weapon.

discharge: The act of firing a gun.

D.O.P.E.: 1. Data on Personal Equipment – The sum of adjustments from a mechanical zero specific to a single shooter and their weapon. 2. Data on Previous Engagement – Data a sniper records in their logbook.

 double barrel: A rifle or shotgun with two barrels mounted side by side. Double barrel weapons may be equipped with two triggers or a barrel selector switch/lever. 

double feed: A stoppage or jam caused by two rounds attempting to enter the chamber at the same time.

double tap: Two shots fired quickly.

dry: An unloaded firearm. Can be used to describe a firearm that has been fired until empty, specifically in thought or dialogue.  

dry fire: The act of practicing with an unloaded firearm.

ejection: The process of clearing a cartridge from inside the firearm. This task is accomplished by the ejector.

ejection port: A window in the frame of the gun that allows spent casings to be expelled.

ejector: A component of the bolt or slide face that ejects the cartridge or cartridge case from the firearm.

experienced recoil: Also known as kick, the amount of force the shooter feels when the gun is fired. Recoil springs absorb some of this force reducing the effects on the shooter. The recoil spring is also an important operational part of automatic firearms.

extraction: The process where a cartridge or cartridge case is removed from the firing chamber. This task is accomplished by the extractor. 

extractor: A component of the bolt or slide that grips the cartridge by the rim and removes it from the chamber when the action is worked.

eye relief: The distance between a magnified scope and the eye where the shooter has the maximum field of view the optic can provide. 

fanning: A quick draw technique for single action revolvers where the shooter draws the revolver with the trigger pulled and fans the hammer with the off hand. Can be used to fire multiple rounds quickly.

field strip: The partial disassembly of a firearm for cleaning and maintenance. This level of disassembly does not require tools.

firearm: Any weapon that propels a projectile down a barrel by burning a propellant.

firing pin: A component of the bolt or slide that impacts the primer on a chambered cartridge. In some firearms, the firing pin may be held in place, under spring tension, by a sear that is released when the trigger is pulled. Other firearms use a hammer to strike the firing pin, forcing it forward to strike the primer.

flash suppressor: A device on the end of a barrel designed to reduce the visible signature of a weapon as it fires.

flier: An errant part of a shot group, not part of the main grouping. In a string of five shots, if four strikes are tightly grouped and the fifth is a noticeable distance away, it’s called a flier. 

flintlock: A device used to fire a musket. The cock was fitted with a piece of flint. When the trigger was pulled, the flint would swing forward and impact the frizzen. This created sparks that would ignite the primer charge in the pan.

frame: The part of the pistol or revolver that houses all internal components of the firearm. Similar to the receiver in rifles.

frizzen: The steel part of a flintlock firing system.

full cock: The final position of the hammer before firing.

full metal jacket (FMJ): See bullet, FMJ 

Garand thumb (a.k.a. M1 thumb): An injury inflicted on the operator when the loading thumb is smashed by the bolt during the loading procedure. This injury is specific to the M1 Garand.

gauge: The measurement of the diameter of a shotgun’s bore.

ghost gun: A firearm with no serial number; assembled from a kit, machined parts, or 3-D printed parts.

grain (gr): A unit of measure used to weigh bullets. 1 gr equals 1/7,000th lb.

grip safety: A mechanical safety on the grip of a firearm that must be depressed in order to fire.

grooves: The recessed portion of a rifled barrel. 

half cock: A safety position of the hammer or cock that allows for safe loading. This position doesn’t permit the trigger to be pulled.

hammer: The part of the gun designed to fire the weapon by either striking a primer directly, or by striking a firing pin, which, in turn, strikes the primer.

hammerless: Any pistol or revolver without an external hammer that could be manipulated by the operator.

holographic sight (holo sight): An unmagnified optical targeting system that projects an aiming point onto the glass. Sights of this type allow for faster engagement of targets.  

iron sights: A simple sighting system consisting of a front and rear sight. They can be made of any material, but the historic name is what’s used.

jacket: The hard metal coating that surrounds the core of a bullet. 

jam: A common term used to describe an unintentional break in the firing cycle. A jam can be either a stoppage or malfunction.  

kick: A common term used to describe recoil experienced by the shooter when the gun is fired. See experienced recoil.

lands: The raised portion of a rifled barrel.

load: (v.) The act of preparing a gun to fire. (n.) the weight of the bullet or the amount of propellant used. 

M1 thumb: See Garand thumb.

machine gun: A firearm specifically designed to be fired in a fully automatic mode.

malfunction: An unintended break in the firing cycle caused by mechanical failure. Malfunctions may be caused by poor maintenance, lack of lubrication, damage to the weapon, or failure of an operational part.

magazine: An internal or external device used to house ammunition and present the next cartridge for loading in manually or automatically operated weapons. Magazines can be tube or box.

magnum: See cartridge, magnum.

manual safety: A mechanical safety that can be visually confirmed as engaged.

matchlock: A device used to fire a musket. It used a slow match to ignite the primer charge contained in an external pan.

MOA: Minute of angle. An angular measurement used to adjust sighting systems on firearms. 60 MOA = 1 degree.

mechanical zero: When a sighting system is adjusted to a completely centered state.

misfire: Failure of the propellant to ignite. In modern cartridges, this can be caused by a faulty primer or a light primer strike. In muskets, this can be caused by a clogged touch hole.

muzzle: The end of the barrel where the projectile exits at high velocity.

muzzle flash: The visible signature of a weapon being fired as flame and hot gases exit the barrel along with the projectile.

muzzleloader: Any firearm loaded through the muzzle. 

nose: The rounded or pointed end of a bullet.

optics: A sighting system, scope, or holographic sight that uses formed lenses and an internal or projected aiming system.

over and under: Any firearm with one barrel mounted underneath the other barrel. 

+P / +P+: Ammunition crafted to create higher pressures that will give the bullet a higher velocity. A firearm must be checked to see whether it can withstand the higher pressures generated by ammunition of this type.

pattern: The distribution of shot at various distances.

pepperbox gun: A firearm with multiple, single-shot barrels housed in a rotating mechanism.

pistol: A handheld firearm with one firing chamber. Pistols can be described by the sizes listed below.

pistol, full-size: Barrel length greater than 4.5 inches.

pistol, compact: Barrel length less than 4.5 inches, but greater than 3.5 inches.

pistol, subcompact: Barrel length less than 3.5 inches but greater than 3 inches.

pistol, pocket: A pistol with a barrel length less than 3 inches.

point blank: Extremely close range.

powder: The propellant used to fire a bullet.

powder, black: A less powerful propellant used to fire a bullet. Black powder is an original formulation of gun powder and produces more smoke and fouling than smokeless powder.

powder, smokeless: A modern formulation of propellant used to fire a bullet. Smokeless powder produces higher energy with a decreased amount of smoke and fouling.

press check: A way to see if a round is chambered. This is accomplished by retracting the bolt or slide far enough to visually confirm that the gun is loaded.

primer: A more energetic chemical compound used to ignite the main propellant.

printing: When a concealed firearm reveals itself as a bulge or shape under clothing.

propellant: A combustible or explosive mixture used to fire a bullet.

pull: See trigger pull. 

rate of fire: A firearm’s rate of fire can be broken down into two categories mechanical and operational. Usually expressed in rounds per minute (RPM), or rounds per second (RPS).

rate of fire, cyclic: The mechanical maximum output the firearm can achieve. This rate ignores source of feed capacity and is strictly dependent on the construction of the gun.

rate of fire, rapid fire: An operational rate of fire which temporarily ignores heat management in favor of superior fire power.

rate of fire, sustained: An operational rate of fire which allows the firearm to be in constant use. This rate of fire considers heat management to prevent damage to barrel and other working parts.

rip – rack – roll – reload: An immediate action drill used to reduce the double feed stoppage.

receiver: The part of the rifle that houses all internal components of the firearm including, where applicable, the bolt, breech block, trigger assembly, and hammer. It also allows for the attachment of external components, such as the barrel, stock, and fore grip.

 recoil: The backward force exerted on the firearm as the weapon is fired. 

recoil pad: A device on the butt of a rifle or shotgun used to decrease experienced recoil.

reflex sight: See holo sight.

reload: (v.) Introducing ammunition into a gun that has expended all rounds through firing. (n.) Any ammunition that uses a casing that has been previously fired. These casings must first be cleaned and fitted with a new primer, propellant, and projectile.

revolver: A handheld pistol with multiple firing chambers contained in a cylinder.

rifle: A shoulder fired weapon with a rifled barrel.

rifling: A helical structure inside the barrel of a firearm made up of lands and grooves. Rifling imparts spin on the projectile, stabilizing its flight and increasing accuracy.

round: a common term used to describe both a bullet and a cartridge of ammunition. 

safety: A mechanical device used to prevent the unintentional firing of a weapon.

sawed-off shotgun: A shotgun with a barrel that has been altered to a length below the legal limit.

scope: An optical aiming device which magnifies a distant target.

sear: A part of the firearm’s trigger assembly that holds back the hammer or striker in a ready to fire position.

semi-automatic: See action, automatic, semi.

shell: A muti-use term used for shotgun ammunition both live and expended. It may also be used for expended rifle and pistol cartridges. See brass.

shotshell: Shotgun ammunition. 

shot: A form of ammunition that uses multiple projectiles fired from a single barrel in one firing.

shot group: The pattern of bullet strikes fired at a single target during a single firing session. Three round groups are usually used when zeroing the sights or optics of a weapon. As a figure of speech, “Tighten up your shot group” is a polite way of saying, “Get your shit together.”

shotgun: A smoothbore firearm designed to shoot pellets, shot, or slugs.

silencer: A misused term for suppressor.

skeet: A shooting sport in which the shooter attempts to hit a clay target while it’s in flight.

slide: An assembly of parts in a semi-automatic pistol that performs the same action as the bolt in a rifle.

slow match: A chemically treated cord designed to burn slowly and consistently. This was the primary ignition source in the first muskets.

slug: A type of shotgun ammunition where, instead of multiple projectiles, there is only one. 

snub nose: A handgun, usually a revolver, with an extremely short barrel.

sporting clay: A flying target used in skeet shooting.

S.P.O.R.T.S: An immediate action drill used to reduce stoppages in AR variant rifles.

standoff: The distance between the gun’s sights and the center of the bore of the barrel.

stock: The part of the longarm that rests against the shoulder. In muskets, the stock acts as a receiver in modern firearms.

stove pipe: A type of stoppage or jam that occurs when a spent cartridge is improperly ejected.

stoppage: A term used to describe an unintentional break in the firing cycle. Stoppages are caused by faulty ammunition, faulty magazines, or in the case of semi-automatic pistols, poor weapon control.

striker: See firing pin.

submachine gun: Any firearm designed to fire in the fully automatic mode that uses handgun ammunition.

suppressor: A device attached to the barrel of a firearm used to reduce the amount of expanding gas leaving the barrel when a round is fired. 

tactical reload: the act of inserting more ammunition into a gun’s magazine while in an engagement or battle. For tube magazines this means simply inserting more cartridges. For ejecting box magazines, it means removing the partially fired magazine and inserting a full one.

tap – rack – bang: An immediate action drill to reduce stoppages in semi-automatic pistols.

thumbing: A quick draw technique for single action revolvers where the shooter draws back the hammer with the thumb of the firing hand while drawing the revolver from its holster.

touch hole: In muskets, a small hole through which flame travels from the pan to the powder in the barrel.

trajectory: The flight path of a projectile from muzzle to target.

trapdoor: An early design for breech-loading rifles. Also, some firearms with internal box magazines have a trapdoor that allows for easy unloading without having to cycle the action until the magazine is clear.

trigger: The part of a firearm that a shooter activates to fire a round.

trigger, hair: A trigger which requires less force to activate.

trigger lock: A form of safety.

trigger pull: The amount of force required, measured in pounds, to activate a trigger. 

velocity: The speed at which a bullet travels.

wad/wadding: Material used to insulate a projectile or shot during the firing of a gun.

wheellock: A firing system for muskets that used a spring-driven wheel to create sparks that would ignite the primer charge in the pan.

Winchester: A term used by the US military that means you’ve expended all your ammunition.

zero: The sum of adjustments needed to make point of aim equal to point of impact at a given distance.

zeroing: The procedure used to make the point of aim the same as the point of impact at a specific distance. This is performed in incremental steps where the strike of the rounds fired are observed and adjustments are made to the sighting system.

zip gun: A crude firearm made with unrifled pipe for a barrel and a rudimentary firing system.