Best LIVE Ammo Deals Online >>>
We review products independently. When you buy through links on our site, we may earn a commission to help support our testing. Learn more.

How Guns Work: Parts of a Gun & Cartridge

45 Colt Guns and Ammo
How do guns work?!? We'll quickly cover how they work, components of a bullet, various actions, and loading mechanisms.
We review products independently. When you buy through links on our site, we may earn a commission to help support our testing. Learn more.
JUMP TO SECTION Jump To:

    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

    Loading…

    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 but still act on the basic premise of a metal tube filled with explosive 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.

    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 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.

    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.

    Ultrasonic Cleaned Firing Pins
    Ultrasonic Cleaned Firing Pins (AR-15)

    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.

    Burning Smokeless Powder
    Burning Smokeless Powder

    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.  

    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?

    LATEST UPDATES

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

    The Best Gun Deals, Coupons and Finds

    Subscribe to Pew Pew Tactical's sales and deals email.

    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

      Good

      February 15, 2016 7:03 pm
      • ehung

        Thanks!

        February 15, 2016 8:07 pm
      • reza

        will

        March 16, 2021 5:54 am
    Join the community! Log in
    Please provide a valid email address.
    Password is required.
    or
    Register
    Please provide a valid display name.
    Please provide a valid email address.
    The password should contain at least 8 characters with at least one number or special character.
    Please accept in order to continue.
    By unsubscribing, you will not be able to access exclusive training courses in your profile. You will still be able to save and access your products and articles.
    or
    Trouble logging in?
    Type your email address and we’ll send you a link to reset your password.
    Please provide a valid email.
    Password
    Type your new password and hit button below to confirm it.
    Field is required.
    Account already exists
    We already have an account registered for email address () which is linked to your Facebook account.
    To log in type your Pew Pew Meter password below.
    Field is required.
    Account already exists
    We noticed that you have previously logged in with your Account which is linked to the same email address () - we can link both of your accounts together.
    In order to link your accounts, hit button below and log in to your Account with the same email as above.

    Account in Pew Pew Tactical means more.

    Login or create a free account to get the following
    Access and save hundreds of reviews, gun guides, and articles!
    Find the best daily deals on guns, gear, and ammo
    Manage your newsletter subscriptions and comments