Action: Part of the firearm that contains the moving parts to load, unload, and fire.
Barrel: The part of the firearm through which projectiles travel when the firearm is fired.
Birdshot: A type of shotgun ammunition with small BBs or pellets of varying size. Typically used to shoot clay birds, hunt real birds, and used in competition. Compare with buckshot.
Bolt: Piece of the action that manually slides back and forth, ejecting a spent cartridge and replacing it with a new one.
Bore: The hollow part of a firearm barrel.
Breech: End of the barrel closest to the user.
Buckshot: A type of shotgun ammunition with larger BBs or pellets of varying size. Typically used in home-defense, law enforcement, military, and hunting applications. Compare with birdshot.
Bullet: Metal projectile that exits the firearm. If the bullet has not been fired, it can be referred to as a cartridge or a round.
Butt (buttstock, stock): Part of a firearm to which the barrel, receiver, and firing mechanism are attached. The end of the stock goes against your shoulder.
Buttpad: Often a piece of soft rubber that goes on the end of the butt to absorb recoil and make shouldering the rifle more comfortable.
Caliber: The diameter of a bullet at its widest part, measured in either inches or millimeters.
Cartridge (shell/round): Holds the bullet, primer, and powder to make a loaded round.
Centerfire ammunition: Ammunition that has a primer in the center of the cartridge’s headstamp. Spent cartridges can be reloaded.
Chamber (breech): At the breech end, the area where the cartridge is seated. Chamber can also be used as a verb, as in “chamber a round in the gun,” which means to load a round into the chamber.
Cheek weld: On long guns, this is the position during shooting in which your cheek has solid and secure contact with the comb of the buttstock.
Clip: A device that holds ammunition and allows the user to speed-load a firearm. A clip can be quickly identified by its lack of spring, as compared to a magazine.
Comb: The top part of a long gun’s stock where the user’s cheek rests during shooting.
Cylinder: Part of a firearm that holds the rounds and (depending on the particular gun) cycles either clockwise or counterclock with each cocking of the hammer and/or pull of the trigger.
Double-action: Two actions are performed with each trigger pull: cocking and dropping the hammer/striker.
Follower: In a magazine, a plastic or metal piece that pushes unspent rounds up the magazine body and into the chamber of a firearm.
Forearm/Forend: On long guns, a metal or wooden piece that either partially or completely encloses the barrel. Enables the user to hold the long gun around the barrel for better stability and maneuverability.
Frame: Piece that houses the action parts and, in a semiauto pistol, connects to the slide. The frame is the core pistol part to which everything else (grips, barrel, trigger, slide, cylinder, etc.) is attached.
Full Metal Jacket (FMJ): A way to describe a bullet that is fully covered, or jacketed, in metal. There are other types of bullets that have hollow points, flat noses, etc., and are not completely jacketed. FMJ bullets are very common, often used for target practice and plinking.
Fully-automatic (full-auto): When the user holds the trigger down, the gun will keep firing until there is no more ammunition in the gun.
Gauge: A way to measure shotgun shell sizes. Common sizes are 12-gauge, 20-gauge, and .410. Based off an English measurement system that confuses even seasoned shooters.
Hammer: Part of the firearm that slams down on a cartridge primer.
Hangfire: When the shooter pulls the trigger and there is a click, the primer is hit, but no bang. However, the round unpredictably goes off anywhere between 1–30 seconds later.
Hollow-point: A type of bullet that has a hollowed cavity at the tip. Typically designed to expand upon impact, causing maximum internal damage to the target. Hollow-points have a reduced risk of over-penetrating the target and reduce the risk of collateral damage. Hollow-points are very common in self-defense situations.
Magazine: A device to hold ammunition that allows the user to speed-load a firearm. A magazine can be quickly identified by the existence of a spring pushing a follower.
Misfire: When the hammer drops on the primer or rim but the round fails to go off. A misfire is similar to a hangfire except that a misfire does not result in a discharge.
Muzzle: The end where the bullet leaves the barrel.
Primer: Part of the cartridge that, when struck by the firing pin or hammer, ignites the primary powder charge.
Pump-action: A firearm with a sliding forearm that manually opens and closes the action after each shot.
Receiver: Part of the firearm that houses the moving and operating parts such as the bolt, trigger, magazine port, latches, switches, etc. In pistols, also referred to as the frame.
Recoil: The backward action of a firearm upon firing.
Rimfire ammunition: Ammunition that has a primer on the rim of the cartridge’s headstamp. Spent cartridges cannot be reloaded.
Safety: A mechanical switch on a firearm that prevents a firearm from discharging. Not all firearms have a safety, and safety mechanisms can fail. ALWAYS follow the four rules of safe firearm handling.
Semiautomatic (semiauto): An action or mode in which the user pulls the trigger and only one shot occurs. The user can then repeatedly pull the trigger to fire additional single shots with each pull until there is no more ammunition in the gun.
Sight alignment: The process of aligning the rear sight and front sights.
Sight picture: The view the user sees of the sights on the target.
Sights: Helps the user aim a firearm. Can come in multiple forms such as iron sights, optical, laser, and peep.
Single-action: One action, dropping the hammer/striker, is performed with each trigger squeeze.
Slide: Top part of a pistol that houses the barrel and other parts.
Striker: A spring-loaded firing pin.
Slug: A type of shotgun ammunition that is essentially a large bullet. Can also be a pistol bullet.
Squib: When the powder ignition fails to create the normal amount of pressure, and the bullet may or may not exit the barrel.
Tap and rack: A malfunction clearance procedure in which the user aggressively “taps” the magazine to make sure it is fully seated and then “racks” the slide to clear and chamber a round.
Trigger: Part of the firearm that is pulled to drop the hammer/striker.
Trigger guard: Piece that protects the trigger from accidentally going off from inadvertent bumps, mishandling, etc.