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Anatomy of a Pump-Action Shotgun | A Guide to Parts and Function

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Pump-action shotguns are among the most iconic firearms available, boasting a history spanning over a century. Their enduring popularity continues to make them a top choice for enthusiasts and beginners alike. 

Despite their widespread use, many enthusiasts and novices remain unfamiliar with the key components that define these firearms. In this guide, we delve into the history, construction, and essential components of the pump-action shotgun. 

What is a Pump-Action Shotgun?

To put it simply, a pump-action shotgun is a shotgun that uses a pump to chamber and eject shot shells. After firing, the user pulls back on the handle to eject the spent shell and pushes it forward to load a new one. While pump actions can be found in other firearm categories, they are most commonly associated with shotguns. 

The first pump-action shotgun ever made in America was built in 1892 by Christopher Miner Spencer. Its effective design set the standard for newer shotguns of the time, and it wouldn’t be long until the predecessor of the legendary Winchester 1897, the Winchester 1893, would be created.  

Today, there are dozens of manufacturers producing their own take on the traditional pump-action shotgun. Models like the Remington 870 and Mossberg 500 are among the most popular pump shotguns available today.  

Even more, you can find more than just the standard 12-gauge shotgun. Regardless of which model you look at; they can come chambered in .410-, 20-, and 12-gauge, giving you plenty of options based on your preference. 

If you’re considering acquiring a pump shotgun, it’s vital to understand what makes a good one and to become familiar with its main components. 

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Key Components of a Pump-Action Shotgun

While there are a lot of variations of the pump-action shotgun, the main components are practically universal: 


The barrel is arguably one of the most critical components of your shotgun. Shotguns come with a wide variety of barrel lengths, ranging from short 18.5″ defense guns to full 30” hunting and sporting guns. As with rifles and pistols, a longer barrel does increase projectile velocity, which can be helpful for bird hunting. That said, don’t expect to see extreme differences. For birdshot, the difference between an 18.5” barrel and 30” barrel may be less than 100 feet per second. 

One of the main benefits of a long barrel is in controllability and magazine tube capacity. A pump-action shotgun with a long barrel will be weighty and controllable, especially when tackling shots against birds in flight. It’ll also likely have a longer magazine tube, which increases your shell capacity for repeated shots. Conversely, a long barrel is considerably heavier, so if you’re hiking out in the wilderness or maneuvering corners indoors, a shorter barrel may be more practical. 

While barrel length can affect spread, your choke will usually play a larger part. Most shotgun barrels come with internal threads at the end for a choke. A choke is a tapered tube that threads into the end of your barrel that can alter that projected pattern of the shot. For example, a narrow choke can keep the shot spread tighter, while an open choke can cause it to spread quicker. Whether you have hunting or defense in mind, there’s a wide variety of chokes to choose from. 

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Also, one noteworthy legal requirement is that shotguns must have a minimum barrel length of 18 inches. Barrels shorter than 18 inches require you to get a tax stamp, registering it with the ATF under the National Firearms Act. Exceptions like the Mossberg 590 Shockwave, with a 14.375-inch barrel, are not classified as shotguns but rather as “pistol grip firearms.” 


The receiver, or frame, serves as the primary component housing the shotgun’s essential parts, including the barrel, magazine tube, and stock. Receivers can be made of either aluminum or steel, depending on the shotgun model. Additionally, the location of controls like the safety and action lock may vary among models. 

Magazine Tube

In most pump-action shotguns, shot shells are stored in the magazine tube, loaded from the bottom, and then chambered upon working the pump action. This design maintains the shotgun’s compact form without a removable magazine. 

Some manufacturers offer models with removable magazines for quicker reloading, but these systems are often less reliable. Additionally, it’s important to note that loaded magazines cannot be stored long-term due to the polymer construction of shot shells, which may deform under extended pressure. 

Fore-end/Slide Action

Sometimes referred to as the ‘pump’, the forend is also what’s used to work the action of the gun to cycle its ammunition. After firing, you would pull it back to eject the spent shell and push it forward to load in a fresh one.  

The forend, or slide action, acts as the grip for the pump on a pump-action shotgun. Just like how you would grip the handguard on a rifle like an AR-15, shotgun forends acts as the grip for the pump action, offering a secure point of contact to prevent burns from the hot metal. 

Trigger Assembly

Found in all firearms, the trigger assembly serves as a mechanical lever initiating the firing sequence. These assemblies are relatively simple and can often be replaced with upgraded versions like those offered by Timney. 

Stock and Grip

Stocks and grips serve as your rear points of contact when shooting. A pump-action shotgun can have a different type of stock depending on the model. Some stocks have the grip integrated into it, like what is found on older/traditional style shotguns. Others have separate stocks and pistol grips, like those found on newer/tactical style shotguns.  

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Upgrading these components is relatively straightforward and allows customization to suit various purposes. 

Safety Mechanisms

Each pump-action shotgun model is going to have a different safety, but they work the same fundamentally. The safety is used to ensure that the gun will not fire by blocking the action. Like other features, the placement of the safety varies from model to model, but each works similarly. 

How a Pump-Action Shotgun Works

As we said previously, pump-action shotguns are some of the simplest firearms to operate. However, to those unfamiliar with them, they can have a slight learning curve upon first operation.  

Firing Cycle

Pump-action shotguns work by manually ejecting and loading in shotgun shells by pulling and pushing the pump of the firearm.  

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After you’ve loaded your shotgun shells into the magazine/magazine tube, with the safety disengaged, pull the forend back, towards you. This will pull the bolt back, allowing for a fresh round to be chambered. After this, push the forend back towards the front of the gun. This will chamber a new shell into your shotgun while also cocking the trigger. You can now pull the trigger, firing your shot shell down range. 

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Something else to consider, most pump action shotguns will lock the action once a shell has been chambered, preventing you from ejecting a shell. To mitigate this, most models have an action release lever or button that can be pressed to free the action, giving you the ability to eject an unfired shell or just to open the action, if ever needed.  

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Variations and Modification

Most shotgun manufacturers offer their products in a variety of configurations, with different barrel lengths, furniture, sights, and more. Some manufacturers even make models with additional upgrades that aren’t found on the base models they create.  

Common Variations 

Manufacturers will often create a few different variations of their shotgun models, with each tailored for either different strengths or benefits.  

Popular options like Remington’s legendary 870 model pump-action shotgun has numerous configurations from the factory that fit different roles. For instance, the standard 870 pump comes standard with either an 18 or 20-inch barrel, but shorter magazine tube along with standard polymer or wood furniture. While the standard model is still a great shotgun, the 870 Tactical features an extended magazine tube, enhanced sights, and the option of standard or upgraded Magpul furniture. Compared to the 870 Fieldmaster, they are very different, as the Fieldmaster is designed for hunting. It can come with either an 18-, 21-, 26-, or 28-inch barrel, and comes standard with a 4-shell capacity.  

Models like the Mossberg 500 and 590, though relatively similar, have their differences. For instance, the 500 weighs less since it uses more polymer, making it more maneuverable, albeit with a smaller round capacity of 6 shells (5+1). In contrast, the standard 590 models are built to be more durable, with the main difference between the two being the thicker barrel and more durable receiver found on the 590. Both variants have a similar look, can have the same barrel length, and have similar aftermarket parts availability, but the 590 is the more durable option. 

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Shorter barrel lengths will make your shotgun more maneuverable in close quarter environments like in your home. In the United States, shotguns are required to have a minimum barrel length of 18 inches, though. Any shorter and it will have to be registered as an SBS and will require that you apply for and purchase a tax stamp to legally own it. Fortunately, 18-inch barrels are more than compact enough to provide you with enough maneuverability to move from room to room.  

Common Upgrades 

There are a lot of upgrades you can make to your pump-action shotgun, especially if you have one of the more popular models on the market. If you’re buying with home defense in mind, tactical upgrades like ergonomic grips and stocks will provide you with lighter weight and more comfortable alternatives to the standard furniture that comes on most shotguns.  

These stocks give you the option to add additional rubber butt pads to help with absorbing recoil, sling mounts, and the option for higher cheek risers. Magpul makes one of the most sought-after stocks, that being their SGA stock.  

Other furniture upgrades like new forends can not only give you a better grip but they can also come with M-LOK attachment points or picatinny rails for additional accessories like lights and sling mounts. A great example is the MOE shotgun forend from Magpul. Shotgun accessories can give you an advantage in numerous scenarios, and the beauty of customization is that you can personalize to fit your needs/wants.  

Another common upgrade is new shotgun sights. Many pump-action shotguns have screw mounts on top of the firearms. These are there so you can add optic mounts to your gun, most commonly in the form of a picatinny rail. This opens up the possibility of running a myriad of optics on your shotgun. A great starting option is a red dot with an option for an open circle reticle, like the Holosun AEMS and 510C.  

One of the major drawbacks found on shotguns is their ammo storage. Side saddles solve this problem. A shotgun side saddle is essentially a shell holder that mounts to either the side of the receiver or stock of the shotgun; they usually hold anywhere from 5-6 extra shot shells. Depending on the mount, some side saddles, like the SureShell carrier from Mesa Tactical, have an additional picatinny rail, giving you both extra ammunition storage and an optic mount.  

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Maintenance, Proper Care, and Safety 

Proper maintenance is crucial for any firearm’s performance. Before cleaning, always remember to adhere to the strict rules of firearm safety. Always check to see if your shotgun is loaded before disassembling or performing a function check.  

Begin with field-stripping your shotgun. You can then use a bore brush or bore snake with a solvent to remove carbon buildup from inside the barrel. Cleaning patches can also be used; you’ll know it’s clean when they can be pulled out from the barrel free of carbon.  

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As for the other components, use a solvent and a brush to knock off any carbon buildup, and then apply oil to lubricate them and prevent them from rusting when in storage. It’s important to avoid over lubricating your gun’s components. Over lubricating your firearm can lead to dirt and dust building up on the inside of your gun, which can impede the action and give it a gritty feeling when operating it.  

Also, don’t forget to do a proper function check after reassembling your shotgun. Once you have verified that the shotgun is completely unloaded, rack the action and pull the trigger to make sure the hammer drops. Once you’ve completed the function check, you’re ready to store it away until it’s time to use it again. Always do your best to keep your firearms stored in a secure, dry space; if any moisture gets to your firearm, it can cause it to rust over, which can lead to further problems if left uncared for.   

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There aren’t many firearm platforms that are as iconic as the pump-action shotgun. Whether you’re wanting one for home protection/defense, hunting, or plinking at the range, they always make for a fine addition to your collection.  

It’s important to be educated before buying a new firearm, and we went over a lot of information about pump-actions pretty quickly. Check out our tactical shotguns guide and our beginner’s guide for guns for self-defense to learn more about what you can best utilize for defense.  

Understanding the anatomy of your firearm is the best way to get prepared to own it, and knowing how your pump-action shotgun works empowers you to use it whenever the need arises.