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Basics of Ammunition - Sizes, Types and Variations

Ammo Case Types

Basics of Ammunition

Modern ammunition varies in size, appearance, materials and parts. Rifle ammunition is called cartridges or rounds. Shotgun ammunition is referred to as shotshells or shells. Ammunition is classified as centerfire or rimfire.

It is important to understand the basics of ammunition and ammunition safety. Knowing the proper ammunition to use will help you become a more successful, ethical hunter.

Ammo Parts

Parts of a Cartridge


These come in a number of different shapes and sizes. They are made of lead and may have metal jacket such as copper. Most hunting bullets are soft or hollow pointed. Designed to expand upon contact with game.


Cases are generally made of brass, nickel plated brass, steel or aluminium. The better quality cases can generally be re-used. This process is called reloading.


A chemical compound which burns (Not explodes) and form gases and push the bullet out of the barrel.


A primer contains a chemical which explodes when struck by the firing pin. A rifle primer may be rimfire of centerfire. *Rimfire ammunition have a primer which is "spun" into the rim area of the base of the case. *Centerfire primers are set into the base of the case.

Ammo Parts

Rim-fire or Center-fire?

The location of the primer tells you if a cartridge is rimfire or centerfire. Generally, center-fire cartridges are more powerful than rim-fire cartridges.
  • The center-fire cartridge has a primer located in the center of the base.
  • The rim-fire cartridge has no noticeable primer. Instead, the priming compound is placed and spun into the case rim. When the rim is struck by the firing pin, the priming compound explodes, igniting the powder.

Ammo Parts

Cartridge Sizes

Ammunition comes in different lengths, shapes, and diameters depending on the type of bullet or case used. If the case is really small, chances are it is a .22 rimfire cartridge.

Years ago a wide variety of rimfire cartridges were available. Today, only .22 rimfire cartridges are commercially available. They can come in 22 short, long, long rifle, and magnum lengths. You will have to learn how to identify them by reading the information on the ammunition box as the data stamp is not on the base of the cartridge.

22 Hornet and 222 Remington use a .22 caliber bullet but use a centerfire cartridge case.

A rimfire cartridge will travel 1300 feet per second while a centerfire cartridge will do over 2000 feet per second. The centerfire case is bigger than the rimfire case and holds more powder.

Ammo Parts

Styles for Cartridges

There are three common case styles for rifle cartridges. Look at the base of the cartridge case to see if the case is rimless, rimmed or belted magnum. Care must be taken when loading rimmed cases into magazines to prevent feeding problems.

Ammo Parts


Bullets come in different shapes and sizes, and are commonly made of lead. Some bullets have a metal jacket, making them travel faster. Full metal-jacketed bullets cannot be used for hunting! They are okay for target shooting.

Ballistics is the science that studies the motion of projectiles. Changing ammunition changes the ballistics for your firearm.

For example, a .30-06 Springfield cartridge with a 180-grain bullet has different ballistics than the same cartridge with a 150-grain bullet. It is important that you sight in your firearm with the same ammunition that you will be hunting with.

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