How Guns Work: Parts of a Gun & Cartridge

This article is a super quick explanation of how guns work.

We'll begin with the easy definition of what a gun is, the different components of the bullet cartridge, some gun actions, and loading mechanisms.

What is a Gun?

At its core, guns are things that launch projectiles of some sort at high speed. The first guns were just tubes with explosives and a projectile...think cannons.

Modern guns have come a long way but still act on the basic premise of a metal tube filled with explosives and some sort of projectile.

Cartridges

What most people think of as "bullets" are actually "cartridges" that include the bullet, a casing, powder, and a primer.

Of course, there are TONS of different calibers (sizes of bullets).

The primer is first ignited causing a small explosion, which then burns the rest of the powder, creating lots of pressure that moves the bullet out of the gun.  

The bullet is just the projectile that shoots out of a gun, not the entire object.

To get a lot more in-depth for each part of a cartridge...check out our Ammo 101: How Cartridges Work.

Here are cross-sections of a variety of pistol/rifle cartridges. Not to scale with each other.

And some cutaways for the different types of shotgun shells.

For more info:

• Common Pistol Calibers
• Common Rifle Calibers
• All About Shotgun Shells

How Guns Work

Different types of guns have different mechanisms for igniting the primer to burn the gunpowder, but there is almost always a rounded metal object called the "firing pin" that strikes the primer and starts the process.

Modern smokeless powders don't even burn that fast...it's the pressure of the confined space of the chamber that gives it the oomph to move the bullet down the barrel.

Below, you can see that the firing pin is attached to a "hammer" in a revolver.

While in a rifle, it could be by itself and held in a "bolt."

Here's some footage of me shooting!

Loading Mechanisms

Most guns will have a mechanism that gets rid of the spent casing and moves in a fresh cartridge.

Some of these include manual actions, using the recoil from the explosion, or using expended gas from the explosion.  

Additional Learning

Looking for a comprehensive handgun video course that only goes over the most important stuff...with none of the attitude? Check out our very own Gun Noob to Gun Slinger course.

Want some of our gun suggestions?

• Best 9mm Handguns
• Best AR-15s
• Best Tactical Shotguns

LATEST UPDATES

June 21, 2024 – Added video to top and updated pictures and content.