What Is a Bullet Cartridge and How Does It Work?

“Bullet cartridge” refers to the four interlocked components that make up a single round of ammunition. These are:

  1. The casing: which holds the gunpowder, the primer, and the projectile together.
  2. The primer: which is seated at the base of the cartridge and creates the spark that ignites the propellant.
  3. The propellant: which explodes in a controlled way and pushes the projectile forward.
  4. The projectile: sometimes referred to as simply “the bullet.”This is the part of the cartridge that flies through the air towards the target.

Powder Valley is your one-stop megastore for all your reloading supply needs, including brass, primers, bullets, and more from the industry’s leading manufacturers, all at the most competitive prices. Questions about which ammo is the right choice for you? Our knowledgeable experts are here to assist.

Let’s take a closer look at the four parts of a bullet cartridge.


The Casing: What It Is and What It Does

“Casing” refers to the hollow cylinder that holds the propellant. It’s often referred to simply as “the cartridge” or as “brass.”

Most reloaders use a tumbler to clean their spent brass. The tumbling process removes grit and grime that would otherwise damage reloading dies and other crucial supplies.

It’s important to use a suitable cleaning medium such as ground corncobs or walnut shells when running brass through the tumbler. Done properly, the end result is a shiny, polished casing that’s ready for reloading.


How the Primer Creates a Controlled Explosion

At the base of a loaded cartridge is a small metal cylinder known as the “primer.” It’s filled with mercury fulminate or some other type of pressure-sensitive explosive. When the hammer strikes the primer, it starts a chemical reaction that ignites the propellant and forces the projectile through the weapon’s barrel.

Thorough safety precautions are essential when handling primers. It’s especially important to avoid open flames, heat sources, and electrical circuits. Keep your primers in the original factory packaging and use care when pressing them into the casing.

The Propellant: Where It All Happens

In the past, classic gunpowder was used as the primary propellant in cartridges. In the modern era, nitrocellulose-based products are generally used instead due to their greater consistency and reliability.

Make sure you use only the type of propellant recommended in your reloading manual and follow all recommended safety precautions. Deviating from the established guidelines can backfire on you in a big way.

How the Projectile Transfers Force to the Target

The projectile is the part of the cartridge that travels through the air and strikes the target. Most civilian ammunition uses a lead-based bullet wrapped in copper or brass.

When used against a living target, the projectile either expands or breaks apart upon impact. The idea is to achieve terminal results as quickly as possible by causing trauma to multiple bodily organs all at once.

Some projectiles are designed for target shooting rather than hunting or self-defense. These bullets for reloading typically have a soft lead core surrounded by a harder metal such as nickel, brass, or steel. They retain their shape upon impact rather than expanding or breaking apart.

In general, target shooting ammo costs less than other types of ammunition. Check out our online inventory for a wide range of ammo types to suit your needs.

Order Your Reloading Supplies Today From Powder Valley

What is a bullet cartridge? To sum up, the bullet cartridge is comprised of the casing, the primer, the propellant, and the projectile. Powder Valley carries a giant selection of these and other reloading components from the brands you trust, all at the lowest prices and with fast shipping. Browse our online inventory and don’t hesitate to reach out if you have any questions. We’re happy to do everything we can to help you shoot more and pay less.