Shotguns: Complete Guide
Everything you need to know about shotgun types, gauges, ammunition, and accessories
From the iconic pump-action to modern bullpups, this guide covers the history, mechanics, and practical knowledge behind every major shotgun platform -written for curious beginners and experienced shooters alike.
Pump-Action Shotguns
The most popular, versatile, and reliable shotgun platform ever made. Manual cycling means they work with any ammunition, every time.
History
Winchester Model 1897
Designed by John Moses Browning, the Model 1897 was the first truly successful pump-action shotgun ever produced. Listed in the November 1897 Winchester catalog as a 12-gauge solid frame shotgun, it improved on the earlier Model 1893 with a thicker receiver to handle the new smokeless powder shells of the era.
It introduced a "take-down" design where the barrel and magazine tube could be easily separated from the receiver for cleaning or transportation -a feature that became standard in modern pump shotguns like the Remington 870 and Mossberg 500.
Key Facts
- - Over one million produced from 1897 until 1957
- - The U.S. Army purchased it for use in the Philippines at the close of the 19th century
- - Famous "trench gun" variants used in both World Wars
- - Could be "slam fired" -holding the trigger down while cycling the action would fire the gun as soon as the action closed
Remington Model 870
Introduced in 1950, the Model 870 was designed to replace the earlier Model 31. Developed by L. Ray Crittendon, Phillip Haskell, Ellis Hailston, and G.E. Pinckney, it utilized common parts from the Model 11-48 autoloader to reduce manufacturing costs.
Remington launched 15 different variants in 12, 16, and 20 gauges during its first year alone. By April 2009, over 10 million had been produced -making it the best-selling pump-action shotgun in firearms history.
Production Milestones
1M
1966
2M
1973
7M
1996
10M
2009
Mossberg 500
Designed in 1961 by Carl Benson, the Mossberg 500 was created for hunters but quickly adopted by law enforcement for its reliability and low cost. By 1979 it was the first pump shotgun utilized by all major branches of the U.S. Armed Forces.
The modified Model 590 was formally adopted by the military in 1987 with increased ammunition capacity. By 2021, approximately 11 million units had been produced -making it the most-produced shotgun of all time.
Key Milestones
- - 1980: Mossberg 500 Bantam introduced for smaller shooters (shorter stock, available in 20ga and 12ga)
- - 1983: Youth models first appeared
- - 1987: Model 590 adopted by the military (increased capacity)
- - 2021: ~11 million produced -the most-produced shotgun of all time
How Pump Actions Work
A pump-action shotgun operates through a manual cycling mechanism powered by the shooter. This linear mechanical system makes them extremely reliable, simple to maintain, and versatile.
Initial Setup
The shooter fills the tubular magazine with shells. A spring inside the magazine tube provides tension against the shells.
Rearward Stroke (Extraction & Ejection)
Pulling the fore-end rearward unlocks and retracts the bolt. The extractor pulls the spent shell from the chamber, which strikes the ejector and is kicked out of the ejection port. The hammer is cocked and a fresh shell is released onto the elevator (shell lifter).
Shell Lifter
The elevator lifts the fresh shell from magazine-tube level up to barrel level, aligning it with the chamber as the fore-end begins its forward travel.
Forward Stroke (Loading & Chambering)
Pushing the fore-end forward drives the bolt forward, pushing the shell into the chamber. The final portion of travel locks the bolt into position. The gun is ready to fire.
Firing
Pulling the trigger releases the hammer, which strikes the firing pin, which strikes the primer on the shell, igniting the propellant. The cycle begins again.
Because the shooter provides the cycling energy, pump-action shotguns will cycle any load regardless of power level -from light target loads to heavy magnum slugs.
Loading, Unloading & Rendering Safe
Loading a Pump-Action
- Engage the safety (ON / SAFE position)
- Point the muzzle in a safe direction at all times
- Keep your finger off the trigger and outside the trigger guard
- Depress the slide release and pull the fore-end rearward -- visually and physically confirm the chamber is empty
- Insert shells one at a time into the loading port, brass end first, until the magazine spring catches each shell
- Push the fore-end fully forward to chamber a round from the magazine
- The gun is now loaded: one in the chamber, remainder in the magazine tube
Unloading a Pump-Action
- Engage the safety (ON / SAFE position)
- Point the muzzle in a safe direction
- Keep your finger off the trigger and outside the trigger guard
- Depress the slide release and cycle the action fully rearward -this ejects the chambered round
- Continue cycling the action until all rounds have been ejected
- Inspect the magazine tube -look for the follower (NOT the rim of another shell)
- Visually inspect the chamber to confirm it is empty
- Leave the action open to indicate the firearm is unloaded
Rendering Safe
Engage the safety. Unload all ammunition from both the chamber AND the magazine tube. Lock the action open. Visually and physically confirm both the chamber and magazine tube are empty.
Advantages of Pump-Action
Reliability
Manual cycling means it works with any ammunition -light target loads, heavy magnums, slugs, buckshot, or birdshot.
Versatility
Fires the widest range of ammunition types and loads of any shotgun action type.
Affordability
Generally the most affordable shotgun action type. A quality Mossberg 500 or Remington 870 costs significantly less than a semi-auto.
Simplicity
Fewer moving parts mean easier maintenance, cleaning, and repair.
Durability
Robust, simple design is extremely long-lasting. Many 870s and 500s have been in service for decades.
Semi-Automatic Shotguns
Faster follow-up shots and reduced felt recoil. Two main operating systems: gas-operated and inertia-driven.
Gas-Operated
Gas-operated semi-automatics bleed off some of the expanding gases from the fired shell. These gases push against a piston near the magazine tube, which pushes a bar linked to the bolt, opening the action. The bolt ejects the spent shell, and a return spring loads a new round.
Beretta A300
- - Compensating exhaust valve cycles 2-3/4" to 3" loads
- - Self-cleaning gas piston for enhanced reliability
- - Chrome-lined barrel with Beretta Mobilchoke system
- - Reversible safety for left- or right-handed use
- - A300 Ultima Patrol: 19.1" barrel, 3" chamber, 7+1 capacity
Remington 1100
- - Introduced in 1963; over four million produced
- - Gases bleed through ports near the fore-end, driving a steel action sleeve
- - Available in 12, 16, 20, 28 gauge and .410 bore
- - Standard capacity: 4+1 (five total)
- - First semi-auto to significantly improve felt recoil and reliability
Inertia-Driven
Inertia-driven shotguns use no expanding gases. A two-piece rotary bolt locks tighter when the gun recoils backward. A spring inside the bolt compresses during recoil, then pushes the bolt rearward to eject the spent shell and strip a fresh round from the magazine.
Benelli M2
- - Proprietary Inertia Driven system
- - "Floating" bolt remains in place while the gun recoils; spring expands to cycle the action
- - Lightweight, slim profile (no gas components)
- - Favored by waterfowl hunters and competition shooters
Benelli M4 (ARGO)
- - Actually gas-operated (ARGO: Auto-Regulating Gas-Operated)
- - Adopted by the U.S. Marine Corps as the M1014 in 1999
- - 18.5" barrel, 5+1 capacity, 7.8 lbs
- - Picatinny rail for optics and accessories
Stoeger M3000
- - Benelli-family inertia system at roughly half the price
- - Return spring on magazine tube (easier to inspect)
- - 3" 12ga chamber; 24", 26", 28" barrels
- - MSRP: $559--$649
Gas-Operated vs. Inertia-Driven
| Feature | Gas-Operated | Inertia-Driven |
|---|---|---|
| Felt Recoil | Less -gas system spreads the impulse over a longer timeframe, producing a softer "push" | More -the gun does not use gases to absorb energy |
| Reliability | Reliable but susceptible to carbon buildup and fouling | Extremely reliable, especially in cold or wet conditions |
| Maintenance | Requires more frequent cleaning due to gas fouling | Fewer parts, less cleaning required |
| Light Load Cycling | Better at cycling lighter loads (7/8 oz target loads) | May struggle with light loads; some require a break-in period |
| Weight | Heavier -gas pistons and springs add weight | Lighter -no gas system components around the fore-end |
| Fore-end Profile | Bulkier / thicker | Slimmer |
Advantages of Semi-Automatic
Reduced Felt Recoil
Especially gas-operated models -the gas system absorbs and spreads recoil energy.
Faster Follow-Up Shots
No manual cycling required between shots; the action does it for you.
Less Shooter Fatigue
Reduced recoil and no pumping motion make extended sessions more comfortable.
Simpler Under Stress
One less manual operation for the shooter to perform -pull the trigger, and the gun cycles itself.
Break-Action Shotguns
The oldest and simplest shotgun design. The action "breaks" open on a hinge to load and unload -from affordable single-shots to fine sporting over-unders.
A Brief History
The break-action mechanism traces its origins to 1832, when French gunsmith Casimir Lefaucheux developed it alongside the pinfire cartridge to facilitate breech-loading designs.
- 1875: The Anson and Deeley boxlock is invented in England -hammers move inside the action for the first time, perfecting the side-by-side design we know today
- Early 1900s: Over-under shotguns appear as built-to-order high-grade guns from England
- 1930s: John Browning designs the Browning Superposed O/U, making over-unders more affordable
- 1950s: Post-WWII prosperity drives O/U shotguns to mass popularity
Early long-barreled side-by-side shotguns were known as "fowling pieces" for their use hunting ducks and other waterbirds.
Types
Single-Shot
One barrel, one shell. The simplest, lightest, and most affordable shotguns available. The action breaks open on a hinge to load a single round. After firing, the action opens to eject the spent shell. Commonly used for beginner training and small-game hunting.
Side-by-Side (SxS)
Two barrels mounted horizontally beside each other. Each barrel has its own trigger (or a single selective trigger). The traditional "gentleman's gun" -especially popular for upland bird hunting (quail, pheasant, grouse). Valued for light weight, quick handling, and classic aesthetics.
Over-Under (O/U)
Two barrels stacked vertically. The dominant shotgun type in competitive clay target shooting (trap, skeet, sporting clays). The single sighting plane gives shooters a consistent sight picture similar to a single-barrel gun. Typically features a single selective trigger.
Sporting Use
- Side-by-Side: Traditionally used for hunting and sporting pursuits, particularly upland bird hunting. Valued for light weight and quick handling.
- Over-Under: Dominant in competitive clay target shooting (trap, skeet, sporting clays). The single sighting plane provides a consistent sight picture.
- Single-Shot: Used for youth and beginner training, small-game hunting, and situations where economy is the priority.
Bullpup Shotguns
In a bullpup design, the action and magazine sit behind the trigger group, resulting in a dramatically shorter overall length while maintaining a full-length barrel. Extremely compact for storage and maneuvering in tight spaces.
FST owns a KelTec KSG410 in .410 bore -one of the shotguns you can experience in our familiarization courses.
KelTec KSG
12 Gauge- - Dual tube magazines with manual 3-position selector
- - Bottom load/eject -fully ambidextrous
- - Top and bottom Picatinny rails
- - Soft rubber butt pad for recoil management
KelTec KSG410
.410 BoreIn FST's Armory
- - Only dual-tube .410 bore shotgun in the world
- - Bottom ejection and loading -ambidextrous
- - Green fiber-optic front sight with carry handle
- - Virtually recoilless -great for all experience levels
IWI Tavor TS12
12 Gauge- - Rotating triple-tube magazine system (5 per tube)
- - Short-stroke gas piston with adjustable regulator
- - Chrome-lined 4140 steel barrel
- - M-LOK rails and continuous top Picatinny rail
Gauges Explained
What "gauge" means, how bore diameters are measured, and which gauge is right for you.
What Does "Gauge" Mean?
First used in the 1677 book A Light to the Art of Gunnery, gauge is determined from the weight of a solid sphere of lead that would fit the bore of the firearm. A 12-gauge bore equals the diameter of a lead ball weighing 1/12 of a pound. It takes 12 such balls to weigh one pound.
A 20-gauge has a smaller bore -it takes 20 lead balls of that diameter to make a pound. This system originated when shooters bought lead by the pound to make their own ammunition.
Key principle: The smaller the gauge number, the LARGER the bore diameter.
Gauge Comparison
| Gauge | Bore Diameter | Characteristics |
|---|---|---|
| 10 Gauge | 0.775" | Largest common gauge. Heavy and powerful, used primarily for waterfowl hunting. Declining in popularity due to improvements in 12ga 3.5" loads. |
| 12 Gauge | 0.729" | By far the most popular gauge. The most versatile -ammunition available in the widest variety of loads for hunting, sport, and defense. |
| 16 Gauge | 0.665" | Once very popular, now a niche gauge. Balance between 12 and 20 gauge. Ammunition is less common and more expensive. |
| 20 Gauge | 0.615" | Second most popular. Lighter guns, less recoil. Excellent for smaller-framed shooters and anyone sensitive to recoil. Popular for upland hunting and home defense. |
| 28 Gauge | 0.550" | A niche gauge beloved by experienced shotgunners. Known for excellent patterning and surprisingly effective performance. Popular in skeet. |
| .410 Bore | 0.410" | Not technically a "gauge" -named after its actual bore diameter. If measured in gauge, it would be ~67 gauge. Lowest recoil, smallest payload. Requires more skill due to smaller shot patterns. |
Chamber Lengths
Chamber length refers to the internal length of the chamber measured after the shell is fired (shells are shorter when unfired because the crimp has not yet opened).
Critical safety rule: You can always shoot SHORTER shells in a LONGER chamber, but NEVER longer shells in a shorter chamber. A 3" shell fired in a 2-3/4" chamber creates dangerously high pressures.
2-3/4"
Fires: 2-3/4" only
12ga steel payload: ~1-1/8 oz
3"
Fires: 2-3/4" and 3"
12ga steel payload: ~1-1/4 to 1-3/8 oz
3-1/2"
Fires: 2-3/4", 3", and 3-1/2"
12ga steel payload: ~1-3/8 to 1-1/2 oz
Most modern shotguns are manufactured with a 3" chamber. For maximum pattern consistency, match shell length to chamber length, but shorter shells will always function safely.
Shotgun Ammunition
Birdshot, buckshot, and slugs -each designed for different purposes, with dramatically different terminal performance.
Birdshot
Birdshot shells contain many small pellets designed for hunting birds, small game, and clay target shooting. To find pellet diameter: subtract the shot size number from 17, and you get the diameter in hundredths of an inch (e.g., #8 shot = 17 - 8 = 9 = .090").
| Shot Size | Pellet Diameter | Approx. Count (12ga, 1-1/8 oz) | Common Uses |
|---|---|---|---|
| #9 | .080" | ~658 | Skeet, close-range clay targets |
| #8 | .090" | ~461 | Trap, skeet, sporting clays, dove |
| #7-1/2 | .095" | ~394 | Trap, sporting clays, dove, quail |
| #6 | .110" | ~253 | Pheasant, rabbit, squirrel |
| #5 | .120" | ~191 | Pheasant, grouse, turkey (TSS) |
| #4 | .130" | ~169 | Turkey, duck (steel) |
| #2 | .150" | ~117 | Waterfowl, geese (steel) |
| BB | .180" | -- | Geese, long-range waterfowl |
| T | .200" | -- | Long-range geese |
Buckshot
Buckshot shells contain larger, fewer pellets designed for hunting medium and large game (originally deer -hence "buck" shot) and for defensive use. As buckshot numbers decrease, pellet size increases. Average effective range: 30--40 yards.
| Size | Pellet Diameter | Pellet Count (12ga, 2-3/4") | Notes |
|---|---|---|---|
| #4 Buck | 0.240" | 21--28 | Smaller pellets, more of them. Reduced penetration vs. larger buck. |
| #1 Buck | 0.300" | 12--16 | Often recommended as an excellent balance of penetration and wound channel count. |
| #00 Buck | 0.330" | 8--9 | The most popular buckshot size, especially for home defense. The "standard" defensive load. |
| #000 Buck | 0.360" | 6--8 | Largest common buckshot. Maximum penetration per pellet. |
3" magnum #00 Buck shells typically contain 12 pellets vs. 8--9 in 2-3/4" shells.
Slugs
Unlike birdshot or buckshot, slugs consist of a single, high-impact projectile. They deliver significantly more energy at greater distances. Average effective range: 75 yards (rifled slugs) to 200 yards (sabot slugs).
Rifled Slugs
- - Designed for smoothbore barrels (barrels without internal rifling)
- - Angled grooves on the outside primarily allow safe passage through choke constrictions -they do NOT significantly spin-stabilize the slug
- - Effective range: ~75--150 yards
- - More affordable than sabot slugs
- - Allow hunters to use existing bird gun barrels for deer hunting
Sabot Slugs
- - Designed for rifled barrels
- - Projectile sits inside a plastic sleeve (sabot) that engages the rifling for gyroscopic stability
- - Air resistance strips the sabot away after exiting the barrel
- - Effective range: ~150--200 yards, with flatter trajectory
- - More expensive; require a dedicated rifled barrel or rifled choke tube
Choke Tubes & Patterning
Removable constrictions at the muzzle that control the spread of your shot pattern. The tighter the constriction, the denser the pattern at distance.
| Choke | Constriction (12ga) | Pattern % at 40 yds | Best For |
|---|---|---|---|
| Cylinder (CYL) | 0.000" (none) | ~40% | Slugs, buckshot, close-range defensive use |
| Improved Cylinder (IC) | 0.010" | ~50% | Close-range hunting (15--30 yds), buckshot |
| Modified (MOD) | 0.020" | ~60% | General-purpose hunting (25--40 yds), all-around |
| Full (FULL) | 0.035" | ~70% | Long-range (40+ yds), turkey, waterfowl pass shooting |
Additional chokes exist (Skeet, Light Modified, Improved Modified, Extra Full / Turkey) that fall between or beyond these standard constrictions.
Patterning Your Shotgun
Patterning is essential because every shotgun, choke, and ammunition combination produces different results. The standard patterning procedure:
- Set up a target with a 30-inch circle marked on it at 40 yards
- Fire a round at the center of the circle
- Count the pellet holes inside the 30-inch circle
- Divide by the total number of pellets in the shell to get your pattern percentage
- Repeat with different chokes and ammunition to find the best combination for your intended use
Customizations & Accessories
Common upgrades for pump-action and semi-auto shotguns -from stocks and sights to lights and slings.
Stocks & Forends
- Adjustable stocks:Customize length of pull (LOP) to fit the individual shooter's frame, improving control and comfort
- Pistol grip stocks: Vertical grip angle; common on tactical/defensive shotguns
- Collapsible/folding: Compact storage; common on tactical models
- Youth/compact: Shorter LOP for smaller-framed shooters
Side Saddles & Shell Carriers
- Mount directly to the receiver or stock
- Hold 4--6 extra shells within immediate reach
- Receiver-mounted side saddles (e.g., Esstac, Aridus Industries) are the most popular option for tactical/defensive shotguns
Magazine Extensions
- Replace the factory magazine tube cap with a longer tube
- Increase capacity: commonly +1, +2, or +3 rounds
- Simple, affordable upgrade with significant capacity gains
Sights
- Bead sights: Standard on most shotguns; simple, effective for wing shooting and clays
- Fiber optic: Bright, easy to pick up in daylight
- Ghost ring / peep: Rear aperture + front post; excellent for defense and slug shooting
- Picatinny rail + red dot: Increasingly popular for defensive and slug shotguns
Weapon-Mounted Lights
- Attach to fore-end rails or dedicated fore-end assemblies (e.g., SureFire)
- Essential for defensive use in low-light situations
- Always identify your target before engaging -a light makes that possible in the dark
Slings
- Single-point:Quick deployment; the gun hangs at the shooter's side
- Two-point: Most stable carry option; distributes weight across the body
- Essential for any shotgun used for defensive or field purposes
Safety First, Always
This guide is for educational purposes. Hands-on instruction with a qualified trainer is the safest way to learn shotgun handling. All FST training begins with comprehensive safety instruction -you'll learn proper handling, storage, and the fundamental rules of firearm safety before any live fire, in a supportive, judgment-free environment.
Ready to Experience Shotguns Hands-On?
Schedule a familiarization course and try FST's shotguns in person -including the KelTec KSG410 bullpup. No experience necessary.