2nd Amendment Part B: Parts of a Gun

Videos by Felix Peng | Avant-Youth

Gifs by Zephaniah Judge | Avant-Youth

In Part B of our Second Amendment series, we examine the composition and functionality of firearms. We also explain how to fully unload a firearm, as well as discuss the four cardinal rules of safety.

This is the next step in our mission to educate, inform and provide resources to Georgians who would like to learn more about firearms. We also aim to bring general awareness to the matter.

Firearms have changed quite a bit over the years. From the old-school flintlock musket to the six-shooting Colt Peacemaker that cowboys adored, the components have changed radically, thereby changing the weaponry and tool as we know it.

General Components

It will be easier to understand the graphics in this article if we first define some of the main components of a gun. Any parts specific to a certain type of firearm will be described within that section.

Barrel – Tube where a round comes out of a gun caused by an explosion or rapid expansion of gases.

Bolt – A mass of metal that feeds the round from the magazine into the chamber and support it during firing.

Bolt-Action – The locking mechanism that works much like a deadbolt on a door. The user lifts the bolt handle, pulls it back, then pushes it forward and turns the handle down.

Bore – The inside of the barrel of a gun excluding the chamber. It is the channel through which projectile passes when the gun is discharged.

Breech – The open rear part in a gun where ammunition is loaded.

Cartridge – A self-contained unit, comprising case, powder, primer and bullet. Each cartridge can be fed into the chamber, discharged, and the empty one extracted.

Chamber – Portion of the gun where the round is inserted before it is able to be fired.

Ejection Port – An opening in a firearm receiver where expended round shells are ejected from a gun.

Firing Pin – A tiny, rounded piece designed to strike the primer of a round. This detonates the bullet and begins propelling a round down the barrel.

Hammer – The part of a firearm that is used to strike the firing pin, which then ignites the charge in a round of ammunition.

Magazine – Ammunition feeding device attached to certain firearms.

Slide – The fixed, top part of a semi-automatic pistol that moves while a round is fired. The slide acts as the bolt, and houses the firing pin.

Trigger – Mechanism located underneath a gun that, when pulled, begins the firing sequence. This is usually surrounded by a thin strip of metal called a trigger guard.



A revolver is a handgun that is loaded with a rotating cylinder, powered by a hammer at the rear of the gun. Made famous by cowboys of the old west and to an extent, Clint Eastwood, revolvers are known for being extremely reliable. This is because the revolver has so few parts for functionality–it’s a very simple machine.

Pictured below, you will see a revolver being opened by a small latch behind the cylinder, also known as the cylinder release. Cartridges are put in the rear of the cylinder and then closed. The cylinder only rotates when the hammer is cocked back or put in “fire” position. This is how one cycles between the cartridges in the cylinder. 

The trigger is the section underneath the frame, protruding downwards from the cylinder with a small metal housing, or trigger guard.

When the trigger is pulled and the hammer goes back to its original state, the revolver will not be able to fire again until the hammer is cocked back once again, rotating a live round into the cylinder.

To unload a revolver, simply open the cylinder and let the ammunition fall back into your hand.


As handgun technology improves, reliability becomes less of an issue. Today, incredibly reliable semi-automatic pistols are widely produced. These handguns carry much higher capacity of cartridges and generally have a higher rate of fire than revolvers. With increased reliability, these new age semi-automatic pistols dominate the handgun market.

Semi-automatic pistols have many more components than revolvers, so the functionality is a little more complicated. 

Most semi-automatic pistols also have a hammer. As the trigger is pulled, the hammer releases and hits the firing pin. The firing pin hits the back of the cartridge, and the cartridge explodes bullets out of the barrel.

The force from the explosion of the used cartridge forces the slide back, ejecting the spent cartridge and reloading a new cartridge into the gun. This is the basic mechanism for all automatic and semi-automatic weapons.

In the gif above, the model points to the trigger, decocker, and slide release in sequence. Note that the slide is locked back, exposing the barrel.

When the slide is locked back, this indicates that the gun has expended all of its ammunition (i.e., it’s empty). The purpose of a slide release is to make reloading quicker. After replacing the magazine, you hit the slide release–the slide slams forward, putting a new round in the chamber.

The decocker is only available on guns that lack a safety. This returns the hammer from a “cocked” position into a “closed” position that requires a much heavier trigger pull to use the weapon.

To unload a semi-automatic pistol: Simply pull the slide back, forcing the unused cartridge up through the ejection port.

The above sequence is best described like this: The model slides a new magazine into the firearm. From the “locked” position, the model pushes the slide release to chamber a new round. After the round is chambered, the slide is pulled back to unload any ammo remaining in the magazine. 

When a slide is in the “locked” position, it is impossible for the firearm to go off. This is considered the best way to handle a pistol in settings where other people are present.

Long Guns

A long gun is any firearm with a long barrel, designed to be braced against one’s shoulder and held with two hands. 


A shotgun is a type of gun that shoots many small projectiles from a single cartridge. They have a very short range, and are generally used for bird hunting and home defense.

Similar to revolvers, double-barrel shotguns are incredibly simple machines. The only functional parts are the breech, breech lock opener and trigger.

The model first points to both triggers, and then the breech lock opener. To unload a double-barrel shotgun, you must open the breech with the lock opener, and the shotgun shells should pop out fairly easy. 

This is a safe position to carry a double-barreled shotgun. It is easy to tell if the weapon has any ammunition in the breech, and the gun is inoperable unless closed anyhow.


Bolt action rifles are most widely used for hunting and long distance target shooting. 

Though bolt-action rifles and semi-automatic rifles (think AR-15) can shoot the same size rounds, bolt-action rifles have a higher muzzle velocity. This allows a bolt-action rifle to fire greater distances.

The rifle relies on the operator to pull back the bolt to open the chamber, extracting a used round. As the bolt slides forward, an unused round is pushed up from the magazine and closed into the chamber, ready to be fired (shown in graphic).

To unload this firearm: Open the magazine and pull out each round individually. In this case, the magazine is the small tube underneath the barrel, which contains a small opening.

This firearm should be handled with the bolt open, making it unable to fire a round accidentally.

Semi-Automatic Rifles

Semi-automatic rifles function essentially the same as pistols, they just have a few different components. 

Rifles in general shoot rounds at a much higher velocity than pistols. Higher velocity requires a larger charge of gunpowder, so the gun must be capable of taking pressure caused by the detonation of larger rounds. 

Thus, semi-automatic rifles have a slightly different composition with the same basic function: To shoot a round, and then reload a new one into the chamber in one motion.

To illustrate the components of a semi-automatic rifle, we created a video of an AR-15 being taken apart.

Four Rules of Firearm Safety

After all this talk about button pressing and chamber opening, it is imperative to mention these four rules of gun handling.

Many different practices are used to prevent firearm accidents, but if anyone is going to handle a gun in a public place, implementing these four rules are of utmost respect. Respect to the other living beings around you, and respect for the power that exists with all firearms.

#1. Treat every gun as if it is always loaded.

 Very simple. Even if you know you unloaded that revolver last time after going to the range, you better point that barrel at the floor and pop that cylinder open to check.

#2. Never point a gun at anything you aren’t willing to destroy.

Remember the whole respect for the power of firearms thing? It’s easy to become complacent about that power while shooting at a paper target. Guns are not toys.

#3. Keep your finger off the trigger until sights are on a target.

This goes hand-in-hand with #2. Even if you’re willing to destroy a target, there is no need for your finger to be near the trigger unless you’re ready to shoot.

#4. Be sure of your target and beyond it.

Shooting on an outdoor range is a good way to prevent this. It’s necessary to scout the land you’re on when on private property.

Click image for a downloadable template

Graphic by Nicole Colon-Rivera | Avant-Youth

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