Buckshot and Slugs: All You Need to Know about Shotgun Ammo

July 8, 2019

Rifle ammunition comes in hundreds of sizes and designs. Shotgun ammo is relatively simple. There are two types: pellet and slug.

You buy your shotgun ammo based on gauge, not on caliber like you do when purchasing rifle ammunition.

Knowing the basics about shotgun ammo will make you an educated consumer, and help you decide what type of shotgun to buy and what ammunition to load in it.

Shell Components

All shotgun shells have a primer, rim, shell case, and powder.

The case holds together everything that makes up the shell. Located within is the primer, powder, wad, and shot pellets or slug depending on what type of gun you are utilizing. The primer consists of a compound composed of explosive material. When struck by the firing pin it facilitates an explosion that in turn activates the gunpowder. When the powder burns it emits a gas that propels the wad into the shot and out of the bore. The wad’s primary purpose is to guard the integrity of the shot and the gun barrel itself, as well as trap the gas behind the shot charge. The shot, whether it be slug or pellets, is what actually comes into contact with the intended target.

You will find the gauge that the shell is intended for stamped on the bottom of the casing. Always inspect your ammunition before using your firearm to discharge it. For example, if you were to insert a 20 gauge shell into a 12 gauge shotgun, the shell would disappear inside the chamber and become lodged within the gun. This could severely damage your expensive firearm. Furthermore, if you were to insert another shell inside of the chamber and you attempted to fire the shotgun, due to the previous shell being lodged within, the entire gun would explode. This obviously will destroy your gun and could incur serious damage upon your person.


Shotguns shoot shells the same way a rifle or handgun does. You pull the trigger, a firing pin strikes the shell primer, igniting the powder and sending the pellets or slug down the barrel.

With pellets, the wad that holds the shots in place until the pellets leave the barrel falls away shortly after leaving the barrel.

The pellets exit the barrel and spread in a funnel-like or scattering pattern. Hence, you may hear someone call a shotgun a scattergun.

The shell casing, like the brass left over after you fire a bullet, ejects.

Also like a bullet, many shooting and hunting enthusiasts like to reload their cartridges. You can reuse the shell casing by adding a new primer and new shot rounds or a slug.


The caliber of a bullet is a dimensional measurement. A gauge refers to a weight measurement.

The term “gauge” was a weight measurement used for cannonballs back before the 18th-century.

In the UK and elsewhere, instead of gauge shooters refer to the bore.

Each means the same: the weight or gauge of shell equates to the tolerance or type of bore or barrel of the shotgun.


Pellets are small, round, typically lead pieces, like BBs, packed into the shell.

The size of the pellet varies depending on the brand or the use. However, each shell has the same size pellets inside it.

Years ago, pellets were solid lead. Today, manufacturers add antimony. Adding antimony hardens the lead, decreasing the distortion of the pellet as it responds to the heat and pressure when the shell is fired.

Bird Shot

Birdshot is a pellet round that has at least a size nine or larger pellet inside.

Hunters use size nine for small game or clay pigeon shooting. Bird hunters use anything larger than 7½ for larger game birds like pheasants.

The larger pellets can penetrate feathers and bone easier.

Barrel or Bore Size

The most common barrel or bore sizes bought in the United States are 12 gauge and 20 gauge shotguns.

A 12-gauge shotgun has a barrel with an inner diameter of .729 inches.

A 20-gauge shotgun has an inner diameter of .615 inch.

Shotguns also come in other sizes, such as a ten gauge or 28 gauge.


Slugs are basically hunks of lead with a rounded tip rather than a pointed tip that bullets have.

Most slugs come in 12 gauge.

You need to check the manufacturer’s specifications to ensure your shotgun has the tolerances to enable it to shoot slugs without damaging the barrel or choke.

Many municipalities require hunting deer or wild hogs with slugs. Slugs from a shotgun do not travel as far as a rifle bullet. A slugs’ effective range is about 100 yards.

This reduces the risk of long-range accidents in populated areas.

Sabot Slug Rounds


A sabot round has plastic sabots used in rifled shotguns.

The plastic sabot engages the barrel’s rifling.

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