Ammunition Glossary: Terms Every Shooter Should Know
Whether you're new to shooting or a seasoned enthusiast, understanding ammunition terminology is essential. This comprehensive glossary covers everything from basic components to advanced ballistic concepts.
Showing 37 of 37 terms
+P / +P+
Ammunition loaded to higher-than-standard pressure for increased velocity and energy. Only use in firearms rated for +P.
Ballistic Coefficient (BC)
A measure of a bullet's ability to overcome air resistance. Higher BC means better long-range performance and less wind drift.
Brass
The cartridge case material, typically made from an alloy of copper and zinc. Brass cases are reloadable and considered higher quality than steel.
Bullet
The projectile that is fired from the firearm. Only the bullet leaves the barrel—the case stays behind.
Caliber
The internal diameter of the gun barrel, and by extension, the diameter of the bullet. Expressed in either inches (.45) or millimeters (9mm).
Cartridge
The complete round of ammunition including the case, primer, powder, and bullet. Often incorrectly called a "bullet."
Casing/Case
The container that holds the primer, powder, and bullet together. Usually made of brass, steel, or aluminum.
Chamber
The part of the firearm barrel where the cartridge sits before firing. The chamber is designed for a specific cartridge.
Controlled Expansion
A bullet designed to expand to a specific diameter upon impact, maximizing energy transfer while ensuring adequate penetration.
Corrosive Ammunition
Ammunition with primers that leave corrosive salts after firing. Requires thorough cleaning to prevent barrel damage. Common in surplus military ammo.
FMJ (Full Metal Jacket)
A bullet with a soft lead core completely encased in a harder metal jacket. Most common for target shooting and military use.
FPS (Feet Per Second)
The standard measurement of bullet velocity in the United States. Higher FPS generally means flatter trajectory.
Grain (gr)
The unit of measurement for bullet weight. There are 7,000 grains in one pound. Common 9mm bullets range from 115gr to 147gr.
Headstamp
The markings on the base of a cartridge case identifying the manufacturer and caliber.
Hollow Point (HP/JHP)
A bullet with a hollow cavity in the tip designed to expand upon impact. Preferred for self-defense and hunting.
Jacket
The outer metal covering of a bullet, usually copper or gilded metal. Protects the barrel and controls expansion.
Lead Free
Ammunition made without lead components, often required for hunting in certain states. Uses copper or other alloys.
Match Grade
Ammunition manufactured to extremely tight tolerances for maximum accuracy. Used in competition and precision shooting.
Muzzle Energy
The kinetic energy of a bullet as it leaves the barrel, measured in foot-pounds (ft-lbs). Indicates stopping power.
Muzzle Velocity
The speed of a bullet as it exits the barrel. Typically measured in feet per second (fps).
NATO
Ammunition manufactured to NATO military specifications. Often higher pressure than commercial equivalents (e.g., 5.56 NATO vs .223 Rem).
Over-Penetration
When a bullet passes completely through a target and continues traveling. A concern with FMJ for self-defense.
Polymer Tip
A bullet with a plastic tip that improves aerodynamics and initiates expansion. Popular for hunting.
Powder/Propellant
The chemical compound that burns rapidly to produce gases that propel the bullet. Modern ammunition uses smokeless powder.
Primer
A small explosive charge at the base of the cartridge that ignites the powder when struck by the firing pin.
Reloading
The process of assembling ammunition from individual components (case, primer, powder, bullet). Also called handloading.
Rimfire
Cartridge design where the primer is contained in the rim of the case base. Examples: .22 LR, .17 HMR.
Round
A single complete unit of ammunition. Synonymous with "cartridge."
Sectional Density
A bullet's weight relative to its diameter. Higher sectional density generally means better penetration.
Soft Point (SP)
A bullet with an exposed lead tip for expansion, but with a jacket covering most of the bullet. Good for hunting.
Steel Case
Cartridge cases made from steel instead of brass. Less expensive but not reloadable and may not be allowed at some ranges.
Stopping Power
A subjective term describing a bullet's ability to incapacitate a target. Influenced by caliber, velocity, and bullet design.
Subsonic
Ammunition with a muzzle velocity below the speed of sound (~1,125 fps). Quieter, especially with suppressors.
Terminal Ballistics
The study of a projectile's behavior upon impact with a target. Includes penetration, expansion, and energy transfer.
Trajectory
The curved path a bullet follows due to gravity and air resistance. Flatter trajectories are easier to shoot at distance.
Velocity
The speed of a bullet, typically measured at the muzzle in feet per second (fps) or meters per second (m/s).
Wadcutter
A flat-fronted bullet designed to cut clean holes in paper targets. Common in .38 Special target loads.
Learn More
Ready to Buy Ammunition Online?
Now that you know the terminology, shop with confidence.
Shop All Ammo