Your ultimate guide for common firearm terms

Welcome to the Gunbuyer firearms glossary. Gunbuyer is committed to helping our customers, including those new to firearms, find the correct firearms, ammunition, and accessories for their particular needs. We understand that the names and terms used to describe the products we sell can be confusing to someone new to the firearms world. That’s why we have created this firearms glossary. Here you will find explanations to the terms most often used to describe the products listed on this website. By using this glossary, it is our hope that you are better able to find exactly the right products and accessories for your individual needs.


The physical mechanism that seals the breech and/or manipulates cartridges. The term explains the method in which cartridges of ammunition are loaded, locked, and extracted from that mechanism. Some examples would be: Single Action, Double Action, SA/DA, Double Action Only, etc. 
When used as abbreviated above, it generally refers to an AK-47. AK-47 stands for the Avtomat Kalashnikova which is a gas operated 7.62x39mm rifle developed in the Soviet Union by Mikhail Kalashnikov in 1947. 
Ammunition / Ammo
The assembly of a projectile and it’s propellant in a single package. 
Many people believe that “AR” stands for “automatic rifle” – and this would be incorrect. AR originally stood for “Armalite Rifle” and most commonly refers to an AR-15 style rifle when the term is used. 
Automatic Rifle
A self-loading rifle that is capable of automatic fire – where the firearm chambers, fires, and ejects multiple cartridges with a single trigger pull. Also referred to as a “machine gun.” These firearms are strictly regulated under the National Firearms Act (NFA).

The science and examination of a projectile’s path, behavior and effects once a bullet leaves its casing. 
A tube, most commonly metal, through which a controlled explosion or rapid expansion of gasses are released to propel a projectile out the end of the tube (or barrel) at high velocity. 
A type of shotgun shell that is made for hunting birds and waterfowl. Specifically, it is the smallest load for a shotgun comprised of small shot – typically made of lead or steel. 
A type of firearm cartridge that contains gunpowder, but no bullet or shot. When fired, the blank makes a flash and a loud report. Commonly used for the start of races, movies and special effects, reenactments, and training. 
A preservation process where steel is partially protected against rust. It is named for the resulting blue-black finish. 

The container portion of an ammunition cartridge that contains the gunpowder, projectile, and primer. Casings are generally metal, most commonly from brass, steel, and aluminum. Shotgun casings are made of plastic.
The diameter of the inside of the firearm’s barrel determines which ammunition that gun can fire. Examples would be: .45 (fractions of inches) or 9mm (in millimeters).
Carbine / Ammo
A shortened version of a service rifle, generally made for use by cavalry. In modern day the carbine does not have a fixed stock but instead has a variable position stock to make it compact when in storage or close quarters but allows for longer more traditional stock lengths when extended. 
A full assembly consisting of a bullet, gunpowder, shell casing, and primer. When counting It is typically referred to as a “round.” 
The portion of the firearm in which the cartridge is inserted prior to being fired. Rifles and pistols have a single chamber, revolvers have multiple chambers in their cylinders and no chamber in their barrel. 

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