DECOCKER – On double-action semi-automatic firearms, a lever that mechanically lowers the hammer without firing the gun.
DELAYED BLOWBACK – A self-loading firearm whose breechblock and barrel are not positively locked together, but which incorporates a mechanism which initially restricts the breechblock from moving when fired, delaying its opening.
DERINGER – A small single-shot or multi-barreled (rarely more than two) pocket pistol. The design was first produced by Henry Deringer, under the brand name Deringer. When used to refer to any other brand of the same design, derringer is spelled with two r’s and is not capitalized.
DETONATE – To explode with great violence. It is generally associated with high explosives e.g. TNT, dynamite, etc., and not with the relatively slow-burning smokeless gunpowders that are classed as propellants.
DOUBLE ACTION (DA)- A type of firearm that may be discharged either by manually cocking the weapon and then pulling the trigger or by using trigger action to both cock and fire the weapon. Originally used only for revolvers but now common in semi-autos as well, Now it commonly means a revolver or pistol on which a long trigger pull can both cock and release the hammer to fire the weapon. In a revolver this action also rotates the cylinder to the next chambered round.
DOUBLE ACTION / SINGLE ACTION (DA/SA) – A type of firearm that is designed to operate in double action on the first shot, and in single action on the second and subsequent shots.
DOUBLE-ACTION ONLY (DAO) – Is a type of firearm in which the firing mechanism cannot be cocked in a single-action stage. Firing always occurs as a double-action sequence where pulling the trigger both cocks and then fires the gun.
DOUBLE BARREL – A shotgun with two barrels either side by side or one over the other.
DOUBLE FEED – A malfunction in which the spent case fails to eject from a semi-automatic firearm and blocks the chamber. As the fresh round is brought forward it cannot enter the chamber. It is cleared by stripping the magazine from the gun, racking the slide several times to eject the spent case, and then reloading.
DOUBLE TAP – Two shots fired in rapid succession. Generally without getting a new sight picture on the target. If the second shot is fired after a second sight picture is captured it may instead be called a controlled pair.
DOWN RANGE – The area of a gun range where firearms are pointed when they are fired. The area of the range forward of the firing line.
DRAMS – A black powder weight measure or smokeless powder in the case of shotgun ammunition,
DROP SAFETY – A mechanical safety that prevents the gun from firing when it is unintentionally dropped. Some state governments require drop-testing of all handgun designs sold within the state.
DRY FIRING – The operation of a firearm without the use of ammunition, as a means of gaining familiarity and technique. Dry firing must be done very carefully with a verified unloaded gun.
DUD – A round of ammunition that does not fire.
DUMMY ROUND – An inert ammunition-shaped object, used in practice to simulate misfeeds and other malfunctions and also used in dry fire practice.
EAR PLUGS – hearing protection that fits inside the ear canal.
EARMUFFS – hearing protection that completely covers both ears and is usually attached to a headband
EARS – Slang for hearing protection, muffs or plugs. The use of specially designed ear muffs or plugs that reduce the intensity of the sound reaching the ears is of course recommended. Some of the guns are so loud that a single shot can can cause permanent damage to unprotected ears.
EJECTOR – A spring-activated mechanism for the ejection of ammunition or and empty shell casing. On doubles, each barrel has a separate ejector.
EJECTOR STAR – On a revolver, the collective ejector, manually operated through the center of an opened cylinder, when activated, clears all chambers at once.
EJECTION PORT – The opening through which the empty, spent ammunition case is ejected from of a firearm.
EJECTION ROD – The sliding metal dowel located at the muzzle end of a revolver cylinder. After firing, the shooter opens the cylinder and depresses the front end of the ejection rod, which forces the empty cases out of the cylinder.
ELECTRONIC HEARING PROTECTION – Ear muff hearing protection that has internal electronics that amplify human voices while excluding all noises louder than a given decibel rating.
ELEVATION – The setting on the sights of a firearm that controls the vertical placement and the altitude above mean sea level. This is important for long range precision shooting because the air density changes with elevation and affects the path of the bullet.
EXPLOSIVE – Any substance (TNT, etc.) that, through chemical reaction, detonates or violently changes to gas with accompanying heat and pressure.
EXTRACTOR – A device that withdraws or elevates a fired shell casing from the chamber as the breech mechanism (slide) is opened.
EXTERNAL SAFETY – A safety lever found on the outer surfaces of the firearm and accessible to the user.
EYES – Slang for safety glasses or other protection for the eyes. All shooters and spotters are required to wear eye protection while shooting is in progress.
FACTORY AMMO – Ammunition that has been assembled by a commercial vendor of ammunition and sold in retail stores. This is as opposed to Hand loads which have been assembled by individuals and are not typically sold.
FAILURE TO EXTRACT – A semi-automatic firearm malfunction in which the extractor fails to move the empty case out of the way as the slide travels back. A failure to extract often causes double-feed malfunction.
FAILURE TO FEED – A semi-automatic firearm malfunction in which the slide passes entirely over the fresh round, failing to pick it up to insert into the chamber as the slide returns to battery.
FAILURE TO FIRE – Any malfunction that results in no shot fired when the trigger is pulled. Commonly caused by a failure to feed, bad ammunition or a broken firing pin.
FIREPOWER – A volume of fire delivered by a military unit. Incorrectly used by the media to mean the ability of a small arm to be discharged many times without reloading.
FIREARM – A rifle, shotgun or handgun using gunpowder as a propellant. By federal definition, under the 1968 Gun Control Act. Air guns are not, by definition, firearms.
FIRING LINE – A line, either imaginary or marked, from which people shoot their firearms down range.
FIRING PIN – A needle like metal part of a modern firearm that gives a vigorous strike to the primer initiating the firing of the cartridge.
FIRING PIN BLOCK – A type of internal safety that prevents the firing pin from moving forward for any reason unless the trigger is pulled.
FIXED AMMUNITION – A complete cartridge of several obsolete types and of today’s rimfire and center-fire versions.
FLASH HIDER/FLASH SUPPRESSOR – A muzzle attachment intended to reduce visible muzzle flash caused by the burning propellant. Flash reducers lessen glare as seen by the shooter, but do not hide the flash from other observers to the front or side of the firearm.
FLAT POINT OR FLAT NOSE – A bullet shape with a flat nose rather than a rounded one.
FLINCH – Jerking the gun downwards just before the shot fires. Commonly caused by learning to shoot with a gun more powerful then they are ready for.
FOLDING STOCK – A long gun stock that may be doubled over for conveniently compact storage.
FOLLOW THROUGH – Holding the trigger to the rear after the shot has fired, until the sights are back on target, at which time the trigger is released.
FOULING – The gritty residue that cleaned out of the barrel and all areas of the firearm in order to clean it.
FOULING SHOT – A shot fired in a clean rifle barrel to put the barrel into the normal slightly dirty state from which it is fired. Often, a rifle will shoot to a different point of aim with this shot as compared to the subsequent shots.
FOUR RULES – The four universal rules of firearms safety, which apply every single time a firearm is handled in any way or for any reason.
FOREND – That part of the stock forward of the action and located below the barrel or barrels. It is designed to give the shooter a place to hold the front end of the gun and protects the shooter’s hand from getting burned on the hot barrel.
FRAME – The common part of a handgun to which the action, barrel and grip are connected.
FRONT SIGHT – The front sight is placed at the muzzle end of the barrel. It is often (but not always) in the form of a dot or a blade. To attain a proper sight picture and shoot with the greatest degree of accuracy, the shooter’s eye should be focused sharply upon the front sight while shooting, allowing both the rear sight and the target to blur somewhat.
FRONT STRAP – The part of a revolver or pistol grip frame that faces forward and often joins with the trigger guard.
FULL METAL JACKET FMJ – A type of round in which in which the lead core bullet is encased in a harder metal jacket on the front and sides.
GAP- Glock Auto Pistol, a type of ammunition.
GAS – The superheated air and other stuff produced by burning powder. Gas pressure is what sends the bullet downrange.
GAS OPERATED – The superheated air created by burning powder. A gas-operated firearm is one that uses the energy from these superheated gases to work the action.
GAUGE – The bore size of a shotgun determined by the number of round lead balls of bore diameter that equals a pound. It is used like “Caliber” for the shotgun.
GHOST-RING SIGHT – A type of aperture rear sight with a large opening and a thin rim that seems to fade out when the shooter looks through it. Sometimes installed on rifles and shotguns intended for home defense or police use.
GRAINS – A unit of weight measurement used for bullets and gunpowder. The more grains, the heavier the bullet. Powder is also measured by grains, but this is generally of interest only to re-loaders. There are 7000 grains to a pound.
GREEN AMMUNITION – Ammunition that contains no lead in any component.
GRIPS – The handle used to hold a handgun. Often refers to the side-panels of the handle or the method by which the shooter holds the handgun.
GRIP PANELS – The interchangeable surfaces that are installed on the part of the gun that you hold. Users change grip panels to improve the look or feel of the firearm, or to personalize it so that the gun is more suited to a different hand size. Some grip panels are chosen for function, while others are chosen for looks. Common grip-panel materials are wood, plastic, and rubber.
GRIP SAFETY – A passive, external safety typically located on the backstrap, which must be fully depressed to release the trigger. Most 1911-pattern pistols feature a grip safety.
GRIPSTRAPS – The exposed portion of a handgun’s frame, the front strap and backstrap, that provides the foundation for the handgun’s grip.
GROOVES – Spiral cuts into the bore of a barrel that give the bullet its spin or rotation as it moves down the barrel. Technically is is the portion of the bore in a rifled barrel that has been machined away.
GROUP – A gathering of holes in the target. The group size is measured by finding the bullet holes that are the furthest apart from each other and measuring from the center of one hole to the center of the other hole.The closer the holes, the better. Obviously the number of shots fired affect the group size. Typical numbers are three, five and ten. From a statistics viewpoint a three shot group is virtually meaningless as a measurement of firearm accuracy. Five shot groups are acceptable. Some advocate a seven shot group as a good tradeoff between economy and statistical relevance.
GUNPOWDER – Chemical substances of various compositions, particle sizes, shapes and colors that, on ignition, serve as a propellant. Ignited smokeless powder emits minimal quantities of smoke from a gun’s muzzle; the older black-powder emits relatively large quantities of whitish smoke.
HAIR TRIGGER – A trigger that breaks from an extremely light touch.
HAMMER – On guns so equipped, the hammer is the part that rotates to provide the percussive impact on the primer. The firing pin may be struck by the hammer, or the firing pin may be a part of the hammer. Not all guns have hammers. Many guns are equipped with strikers: notably Glock pistols and the vast majority of bolt action rifles. Hammers may be exposed or shrouded, spurred or bobbed.
HAMMER SPUR – The thumb-piece on the top rear of the hammer that enables it to be manually drawn back to full cock.
HAMMERLESS – A revolver or pistol design that actually have hammers but are fully encased inside the frames, hammer designs where the spurs have been removed for concealment, or striker-fired pistols that are truly hammerless.
HANDGUN – Synonym for pistol. designed to be fired while held in one or both hands, rather than while braced against the shoulder.
HANDLOADS – Cartridges assembled by an individual person from the individual components (primer, shell casing, gunpowder, and bullet) and are typically tailored specifically for their firearm.
HARDBALL – Slang for a full metal jacket bullet with a round nose. The term is most commonly used in referring to .45 ACP caliber ammunition, but may be used for other calibers as well.
HEEL (OF A STOCK) -The top of the butt, when the gun is in position on the shoulder to be fired, is called the heel.
HEAVY TRIGGER – A trigger that requires a lot of pressure to pull it past the break point. Rifles tend to have considerably lighter triggers than handguns, and even a heavy rifle trigger is often lighter than a light handgun trigger.
HIGH-CAPACITY MAGAZINE – An inexact, non-technical term indicating a magazine holding more rounds than might be considered “average.”
HIGH KNEELING – A shooting position in which one or both knees are touching the ground, but the shooter is otherwise erect.
HMR – Hornady Magnum Rimfire, a type of ammunition.
HOLLOW-POINT BULLET – A bullet with a concavity in its nose to increase expansion on penetration of a solid target. some hollow-point’s are also designed to fragment as they expand. They are least likely to over-penetrate the target and harm an innocent bystander. Commonly used for self-defense
HOLSTER – A gun holder that may be strapped to a human body, or affixed to the inside of a pack or bag, or dropped into a pocket. A holster serves to protect the gun’s mechanisms and finish, to provide security by covering the trigger so it cannot be pulled inadvertently, and to present the grip of the gun at a constant angle for easy access. Some holsters also serve to obscure the outline of the gun so it may be more easily concealed. Typically made from leather or in plastic.
HOT RANGE – Pistol can be carried loaded, also a range where the range master has given the order to commence fire