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How Guns Work [Visual Guide]

A super quick explanation of how guns work.

Benelli M2, CZ75, AR-15 (3)
3-Gun: Benelli M2, CZ75, AR-15 Stacked

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

Table of Contents


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.

Cannon Blast, Smithsonian Channel
Cannon Blast, Smithsonian Channel

Modern guns have come a long way.


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

Deconstructed 9mm Cartridge
Deconstructed 9mm Cartridge

Of course there’s TONS of different calibers (size of bullets).

Common Calibers in Room
Common Calibers in Room

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.  

Rimfire vs Centerfire Cartridges
Rimfire vs Centerfire Cartridges

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

.308 (168gr vs 208gr)
.308 (168gr vs 208gr)

To get a lot more in-depth…check out our Ammo 101: How Cartridges Work.

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

Cross Section of a Bullet Cartridge
Cross Section of a Bullet Cartridge

And some cutaways for the different types of shotgun shells.

12ga Shotgun Shells, Opened (L to R: Bird, Buck, Slug)
12ga Shotgun Shells, Opened (L to R: Bird, Buck, Slug)

For more info:

How Guns Work

Different types of guns have different mechanisms of how to ignite the primer to burn the gunpowder, but there is almost always a rounded metal object called the “firing pin” which strikes the primer and starts the process.

Burning Smokeless Powder
Burning Smokeless Powder

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.

How a Revolver Works
How a Revolver Works

While in a rifle it could be by itself and held in a “bolt.”

Gas System Gun
Gas System Gun

Here’s some 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.  We’ll go over these in detail in further lessons. But for now, here’s some slow-motion of guns in action.

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.

Pew Pew Tactical Handgun Course
Pew Pew Tactical Handgun Course

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18 Leave a Reply

  • Greg Davenport

    I just took a CWP class and want a Revolver. What would you suggest for a great gun for Both Concealed Carry And Target shooting ?? I’m 71 , and giving my GLOCK 9mm to my son because my thumbs are shot and weak hand strength makes it too hard to load the bullets or slide the GLOCK!! Money is no object !!! Thanks Greg

    February 11, 2020 4:24 pm
    • Jay Turner

      Take a look at the S&W Shield EZ9, specially designed for easy loading and easy racking. My wife and I both use this as a carry gun and home protection with high performance self defense rounds. DO NOT confuse with the regular Shield, it is NOT easy to rack.

      May 15, 2021 6:45 am
  • anthony cutuli

    what is the difference single action, double action

    September 25, 2019 9:42 am
    • Michael

      single action the trigger does not cock the hammer it just relates it, double action cocks the hammer and releases it its also a lot heavier and longer trigger pull.

      April 3, 2021 5:24 pm
  • Dale Gribble

    I really feel like i should be paying for this info. THANK U SO MUCH!!

    November 22, 2018 1:34 am
  • geraldine quesenberry

    This was very interesting. Thank you for helping me understand what my gun is all about.

    April 28, 2018 1:56 pm
  • Deepali Bangera

    Very well explained

    February 9, 2018 10:22 pm
  • Conner Forbis

    Very well done. In-depth enough to remain informative but barebones enough to not be confusing. The diagram you added on an automatic rifle's gas blowback system was particularly good. It's as if you could imagine the gun firing and walking through the steps just looking at it.

    February 9, 2018 10:14 am
    • Eric Hung

      Thanks, Connor!

      February 13, 2018 9:19 pm
  • Joy

    I'm a newbie and I like this! Thank you.

    October 29, 2017 11:21 am
  • cj pickup

    Hey GREAT website, but navigating through these "chapters" in the TUTORIALS, is kinda clunky.
    It would be nice if the chapter sections had a Next button to continue on at the end. (maybe even a Back button)

    July 11, 2017 1:50 pm
  • Chris

    Im 15 and i'm really interested in guns and i'm glad I found this site it's a great learning experience.

    April 8, 2017 3:52 pm
    • Eric Hung

      Thanks so much Chris!!

      June 5, 2017 12:12 pm
  • FT Tern

    Your "cross section of a shotgun cartridge" isn't. :-/ It's a shotshell for use in a handgun.

    December 11, 2016 12:56 am
    • ehung

      Hi FT, you are correct. I've fixed it and thanks so much for catching it.

      December 11, 2016 5:41 pm
  • Miguel Empeynado


    February 15, 2016 7:03 pm
    • ehung


      February 15, 2016 8:07 pm
    • reza


      March 16, 2021 5:54 am