Ammunition and Reloading Glossary

Whether you're a veteran hunter or purchasing your first firearm, knowing the definitions of common ammunition and reloading terms can help you pick out the perfect product for your needs. Here are some of the most popular words and phrases you may come across while shopping online for ammo or reloading equipment.

• Ammunition: Commonly called Ammo, this is the combination of a projectile, primer, and propellant all assembled in a case.
• Ball: A common name for jacketed, round nose projectiles
• Ballistics: The science and study of projectiles in motion
• Ballistic Coefficient (BC): A ratio used to describe the bullet's effectiveness in overcoming air resistance. The higher the number, the more aerodynamic the projectile, which allows it to maintain speed and resist wind drag better. A common expression is that it will "shoot flatter".
• Birdshot: Small metal pellets or balls, called "shot", that are best used for hunting birds or small game. Birdshot can also be used for shooting sporting clays. Shot size can vary from the relatively large "BB" size to the tiny "#12" size.
• Blank: A cartridge that does not have a projectile, often used for training/simulation purposes
• Boat Tail (BT): A taper design at the base of a bullet
• Bonded: A projectile where the jacket has been molecularly attached to the core
• Brass: A common name for empty cases, as most cases are made from brass
• Buckshot: Larger sizes of shot used for hunting medium to large game. Also commonly used for self-defense purposes.
• Bullet: The projectile component of ammunition
• Bullet Weight: The weight of a bullet is expressed in grains, often abbreviated as "gr". Bullet weight makes a difference on how the bullet performs. It will impact how the firearm recoils, and it will have an impact on the overall trajectory of the bullet. Generally speaking, a lighter bullet will have a greater velocity and maintain trajectory better while a heavier bullet of the same caliber will have greater terminal ballistics.
• Bullet Type: Bullets are made in various shapes and constructions depending on the intended applications. They can be made of a variety of materials such as copper, lead, steel, polymer, rubber, and even wax.
• Caliber: The diameter of the projectile, normally measured in inches or millimeters. The term "caliber" is also commonly used in place of "cartridge".
• Cartridge: A complete round of ammunition with all components intact
• Casing: The component of ammunition that contains the powder, primer, and projectile
• Centerfire: A cartridge with the primer located in the center of the case head
• Chamfer: Reaming or beveling a taper to remove burrs
• Charge: The quantity of powder loaded into a case, often expressed in grains
• Components: Parts necessary to create a cartridge (case, primer, powder, projectile)
• Crimp: Turning the case mouth inward slightly to better grip the projectile
• Decap: Removing a used primer from an ejected case.
• Dram: A term used to describe the powder charge for shotgun ammunition
• Dummy: A completely inert round that has no primer or powder. Also commonly called a "snap cap", these are used for dry fire training.
• Flash Hole: Opening in the case through which the spark from the primer travels to ignite the powder
• Frangible: A type of bullet that is designed to disintegrate upon impact. Often used to limit the risk of over penetration or for range safety.
• Full Metal Jacket (FMJ): A type of bullet where there is an outer shell or "jacket" surrounding the core. Also called "Total Metal Jacket" by some manufacturers.
• Gas Check: A device used with non-jacketed bullets to prevent the buildup of lead in the barrel
• Gauge: The unit of measurement used to describe the inner diameter of a shotgun barrel. Shotgun shells are described by "Gauge" rather than "Caliber".
• Grain: Unit of measure of mass used with ammunition components like projectiles or powder
• Headspace: Measurement of the chamber with the breech closed
• Headstamp: The marking on the base of a cartridge case, often designating the manufacturer and caliber
• High Brass: Brass that extends further up the sides of the shotgun shell, often used to differentiate high powered loads from more common loads
• Hollow Point: A type of bullet design in which the core does not extend to the tip of the projectile. Most hollow point bullets are designed to expand on impact, making them ideal for self-defense use.
• Jacket: The external covering of a projectile core
• Low Brass: Commonly used with low power shotgun shell loads, the brass does not extend as far up the side.
• Magnum: A cartridge with a greater powder charge than is typically used with that diameter projectile
• Match Grade: Higher quality components manufactured with stricter tolerances
• Muzzle Velocity: This is the speed of a projectile at the moment it leaves the muzzle of the firearm, which means barrel length affects muzzle velocity. It is most commonly expressed as feet per second (ft/s). Higher muzzle velocities provide a straighter trajectory and often provide better terminal ballistics. Higher velocity ammunition (often labeled "P" or "+P") generally delivers higher felt recoil though.
• Neck: Narrow portion of the case that grips the projectile
• Open Tip Match (OTM): Highly accurate projectiles that have an open tip due to the manufacturing process. They are not designed to expand on impact the way most hollow point or soft point bullets are.
• Ogive: The curved, forward portion of a projectile
• Powder: Highly combustible material that generates gas when burned to propel a projectile
• Pressure: The burning gunpowder creates pressure which forces the bullet out of the case/barrel and towards the target. Overpressure ammunition, commonly designated as "P" or "+P", is small arms ammunition that has been loaded to a higher internal pressure than is standard for ammunition of its caliber. This ammo will have a higher muzzle velocity than standard loads.
• Primer: A percussion cap that when impacted propels a spark into the powder within the case. Boxer primers, which use a single flash hole in the center of the case, are most common in the US and new production brass cartridges. Berdan primers use multiple, off center flash holes and are most commonly found in non-US military surplus ammo.
• Projectile: The part of ammunition that is propelled out of the barrel at a target downrange. Also commonly called a bullet.
• Resizing: Reforming a fired case to the proper dimensions.
• Rimfire: A type of ammunition that has the primer located in the rim of the base of the case.
• Rim: The flange at the base of a case, used by the extractor to remove a spent cartridge
• Round Nose: A type of bullet design that uses a blunt, spherical shape tip
• Sabot: A device, often a sleeve, used to fire a projectile that is smaller than the diameter of the barrel
• Sectional Density (SD): The ratio of a projectile's weight to its transverse section, denoting how well a projectile's mass is distributed
• Semi-wadcutter: Combination of a wadcutter and a round nose projectile that is a conical nose with a flat point
• Shellholder: A device that holds the case during reloading
• Shoulder: Portion of the case that slopes from the body to the neck.
• Shot: Metal pellets or balls used in shotgun shells, whose size is designated by letter or numbers
• Shotshell: A common name for shotgun ammunition
• Shot Material: Generally, "shot" is made from lead, steel, tungsten, or other lead-free materials.
• Shot Size: Shotshells are loaded with different sizes of "shot" or pellets. The smaller the number, the larger the shot.
• Slugs: A single projectile, generally larger than buckshot, used for short-range shooting and hunting large game
• Soft Point (SP): A type of bullet where the jacket does not enclose the tip of the core so that it can expand upon impact
• Swage: Reducing the size of a material with pressure
• Terminal Ballistics: This is the behavior and effects of a projectile when it hits and transfers its energy to a target. Bullet design and the velocity of impact largely determine the effectiveness of its impact.
• Total Metal Jacket (TMJ): Another name for Full Metal Jacket
• Wadcutter: Cylinder-shaped bullet with a flat top and base, used for target shooting due to the uniformly round holes they make in paper targets.