The working mechanism of the handgun. This determines the process by which the handgun is cocked, fired, and reloaded. See the subsequent section on specific types of handgun actions for more details.

A tube of varying length through which the bullet is discharged. Discharging the bullet through the barrel determines the bullet's initial direction and trajectory. The seal created between the bullet and the surface of the barrel keeps the gas produced by the burning gunpowder trapped behind the bullet once it leaves the cartridge case. As a result, the bullet continues to accelerate until it exits the handgun at the muzzle. Thus, the longer the barrel, the higher the velocity achieved by the bullet. Additionally, modern handgun barrels are rifled, which causes the bullet to spin, giving it more stability in flight.

The interior diameter of the handgun's barrel.

The area of the handgun that contains the mechanical action, the chamber and the attachment of the barrel to the frame.

The rear portion of the frame onto which the grip is attached.

The portion of the handgun that holds the cartridge during discharge. The chamber is located directly behind the rifled portion of the barrel. Pistols have a single chamber (an integral portion of the barrel), and the empty casing must be removed and replaced with a new cartridge before another shot can be fired. Depending on the mechanism of action, this process is done either automatically (in the case of semi-automatic pistols) or manually (in the case of Derringers and some single shot competition-style pistols). In contrast, revolvers contain multiple chambers (that are not an integral part of the barrel), each holding a single cartridge, which rotate into the firing position behind a single barrel.

The rotating drum, found on revolvers, which contains multiple chambers. Most commonly, a cylinder will contain six chambers, but some are made with as many as ten. When a revolver is discharged, the cylinder can be manually rotated to bring the next chamber in line with the barrel.

A pin that transfers the energy generated by the hammer to the primer. The firing pin lies behind the cartridge. The impact of the firing pin on the cartridge ignites the primer and causes the powder to burn rapidly, thus discharging the bullet.

The basic structure or housing to which the other components are attached. Also known as the receiver.

The point at which the user holds the handgun during use. Grips are usually made of wood, rubber, or synthetic materials, and can be custom-designed to fit the user's hand. The grip is generally an integral part of the frame.

The mechanism that generates the energy needed to ignite the primer and fire the bullet. When the hammer is pulled back into the cocked position, it compresses the mainspring, thus generating potential energy. When the trigger is pulled, the potential energy stored in the mainspring is released, forcing the hammer down onto the firing pin. The kinetic energy generated as the hammer falls is transferred through the firing pin to the cartridge.

The initial source of the energy needed to fire the gun. Cocking the hammer compresses the mainspring, generating potential energy.

A container that holds cartridges and feeds them automatically into the chamber of semi-automatic pistols. Often the magazine is a removable component which inserts into the grip of the pistol. The capacity of the magazine can vary greatly. The Violent Crime Control and Law Enforcement Act of 1994, however, limited the magazine capacity of handguns to a maximum of 10 cartridges (part of the so-called "assault weapon ban").

The end of the barrel from which the bullet exits.

A set of parallel spiraling grooves that run the length of the interior of the barrel. The grooves cause the bullet to spin as it passes, thus giving it additional stability and accuracy in flight.

A device that can be attached to the handgun to reduce the sound of discharge.

A device that surrounds the barrel on semi-automatic handguns (Figure 5). As its name implies, the slide moves backwards, opening the breech area of the handgun. Also, on many semi-automatic pistols, the backward movement of the slide cocks the hammer. When the gun is fired, some of the energy from the discharge of the bullet is used to push the slide backwards, thus opening the breech to expel the empty cartridge case and recocking the hammer for the next shot.

A loop of metal that extends down from the frame and encircles the trigger. It is designed to prevent the trigger from snagging as the handgun is removed from or placed into a holster.