01 / At a glance
The basics
- Origin
- Traditional bore system
- Introduced
- Long-standing
- Ignition
- Centerfire
- Case form
- Rimmed shotshell
- Diameter
- Gauge
- Case length
- 70 / 76 mm
Rounded values to help you identify the cartridge, not manufacturing drawings. See the cited standard for exact dimensions and tolerances.
Do not mix it up
A 20 gauge shell can slip into a 12 gauge chamber and lodge in the barrel. Never keep 12 and 20 gauge shells together. Shell length must never exceed your chamber.
The 20 gauge is the second most popular shotgun size in the world, after the 12 gauge. It is lighter, softer to shoot and easier to carry, and with modern shells it does most of what a 12 gauge does. Upland bird hunters, clay shooters, youth and smaller-framed adults all rely on it.
Like any shotshell, the 20 gauge has several variables: shell length, shot size, load weight and choke. This guide explains each one, shows how to choose a shell and a shotgun, and compares the 20 gauge with the 12 gauge and other sizes. It is a reference page, not a loading manual, and it contains no handloading data.
A short history
The word "gauge" comes from an old British system. A 20 gauge bore is the diameter of a lead ball that weighs one-twentieth of a pound, so twenty such balls weigh a pound. A smaller number means a larger bore, which is why the 12 gauge is bigger than the 20.
The 20 gauge is old, and it has been used for upland game since the muzzle-loading era. For much of the 20th century it was seen as a light upland gun, while the 12 was the choice for everything else. That changed as shells improved. Better wads, better powders and 3 inch magnum shells let the 20 gauge handle waterfowl, turkey and deer slugs.
Today, a modern 20 gauge with the right load and choke does nearly everything a 12 gauge does, and many hunters choose it for exactly that reason.
Why it is so popular
The first reason is weight. A 20 gauge shotgun is often a pound or more lighter than a similar 12 gauge. Over a day of walking behind a pointer, that is noticeable. Many upland hunters pick it because they simply carry it more comfortably.
The second is recoil. A 7/8 or 1 ounce load kicks noticeably less than a 1 1/8 ounce 12 gauge load. That makes it a good first shotgun for young shooters and for adults who are sensitive to recoil.
The third is variety. Shells for the 20 gauge are made in every common load, from target to magnum, and nearly every shotgun model is available in it.
Specifications at a glance
| Specification | Value |
|---|---|
| Nominal bore diameter | About .615 in (15.6 mm) |
| Common shell lengths | 2¾ in (70 mm) and 3 in (76 mm) |
| Maximum average pressure (SAAMI) | 12,500 psi |
| Common shot loads | 3/4 oz to 1¼ oz; most game loads are 7/8 to 1 oz |
| Typical velocity | About 1,150 to 1,350 ft/s for shot loads |
| Common shot sizes | #9 to BB |
| Slug weight | About 5/8 to 1 oz |
| Typical gun weight | About 5½ to 7 lb |
Values are rounded for reference. Exact dimensions and tolerances are in the SAAMI and C.I.P. standards cited at the end of this page.
Strengths and limits
The 20 gauge is a lighter, friendlier gun. It also has trade-offs you should know about.
| Advantage | Limitation |
|---|---|
| Lighter gun and softer recoil | Smaller shot charge than a 12 gauge in the same load class |
| Good pattern density with a quality load | Fewer choices of specialty shells than the 12 gauge |
| Easy to carry on long walks | Heavy 3 inch magnum loads recoil sharply in a light gun |
| Fits smaller and younger shooters | Shells can cost a little more in some places |
Shot size and what it does
A shotshell fires many pellets rather than one bullet, so pellet size and count matter more than a single trajectory. Smaller shot gives more pellets and denser patterns but less energy per pellet. Larger shot gives fewer pellets with more punch.
A typical 20 gauge load carries about 7/8 to 1 ounce of shot. That means a 7/8 ounce load of #8 holds about 360 pellets, and a 1 ounce load of #6 holds about 225. The chart shows lead shot. Steel, bismuth and tungsten alloys have different densities, so the numbers per ounce are different. Check the box.
| Use | Common shot sizes | Notes |
|---|---|---|
| Skeet and clay targets | #8 and #9 | Light 7/8 oz target loads are popular |
| Sporting clays | #7½ and #8 | More reach for longer targets |
| Dove and quail | #7½ to #8 | Small, fast birds |
| Pheasant and grouse | #5 to #6 | Larger and tougher birds |
| Ducks (steel) | #3 to #4 | Use 3 inch shells and steel-rated chokes |
| Turkey | #4 to #6 | Tight chokes and 3 inch loads are common |
Pellet counts are approximate for lead shot and vary slightly by maker. Always read the box and pattern your shotgun, because every barrel and choke combination shoots a little differently.
Recoil and shooter comfort
Recoil comes from the weight of the shot charge, the velocity and the weight of the gun. A 7/8 ounce target load in a 6.5 pound 20 gauge is mild. A 3 inch magnum with 1¼ ounces in a light gun can be sharp, close to a standard 12 gauge load.
A good stock fit and a recoil pad matter more than people expect. If the gun fits, a 20 gauge can be shot all day. If it does not, it can hurt a lot faster than its size suggests. Gas-operated semi-automatics also soften the kick compared with pumps and fixed-breech guns.
How to choose a shell
Start with the job. Then choose the shell length, the shot or slug, and the load weight.
Shell length
| Length | Typical use | Notes |
|---|---|---|
| 2¾ in (70 mm) | Targets, upland birds, light slugs | The standard; fits every 20 gauge |
| 3 in (76 mm) | Turkey, waterfowl, heavy slugs | Needs a 3 inch chamber or longer |
Load weight
A 3/4 or 7/8 ounce load is the standard for clay targets and light upland work. A 1 ounce load is a good all-round hunting weight. A 1 1/8 or 1¼ ounce load is for larger birds and turkey, and it recoils more.
Lead and non-toxic shot
Many wetlands and some other areas require non-toxic shot such as steel, bismuth or tungsten alloys. Steel is harder and lighter than lead, so it patterns differently. A 20 gauge steel load carries fewer pellets than a 12 gauge steel load, which limits it on large waterfowl. Check the rules where you hunt.
Slugs
A slug is a single heavy projectile for deer and similar game. A 20 gauge slug is effective at short range, and sabot slugs from a rifled barrel can reach farther. Choose the slug type to match your barrel, rifled or smoothbore.
How to choose a shotgun
The right shotgun depends on what you plan to shoot. These are the points that matter most.
- Action. Pump-action guns are reliable and affordable. Semi-automatics soften recoil. Over-and-under and side-by-side guns are classic for upland birds and clay targets, and many are built on a true 20 gauge frame, which makes them lighter than a 12 gauge.
- Chamber length. Check the barrel. A 3 inch chamber fires 2¾ and 3 inch shells. A 2¾ inch chamber must only fire 2¾ inch shells.
- Barrel length. Barrels of 26 to 28 inches suit upland birds and clay targets. Shorter barrels, 18 to 24 inches, are handier for slugs, turkey in brush and defense.
- Interchangeable chokes. Screw-in tubes let you change the pattern for each use. Check that steel shot is approved for your tubes.
- Fit and weight. A gun that fits you shoots better and hurts less. For youth, look for a short length of pull or an adjustable stock.
Chokes and patterning
A choke is a narrowing at the muzzle that controls how tightly the shot spreads. A tighter choke holds the pattern together for longer shots. A more open choke gives a wider pattern for close targets. Because a 20 gauge carries fewer pellets, choke choice matters a bit more than with a 12 gauge.
| Choke | Constriction | Typical use |
|---|---|---|
| Cylinder | None | Close range, slugs, defense |
| Improved cylinder | Light | Upland birds, skeet |
| Modified | Medium | All-around, 30 to 35 yards |
| Improved modified | Medium-heavy | Longer upland and waterfowl shots |
| Full | Tight | Turkey and long-range shots |
Patterning means firing at a large sheet of paper at 40 yards and counting the pellets inside a 30 inch circle. It shows how your gun, load and choke work together. Pattern before the season, not during it.
Practical uses
Upland birds
Pheasant, grouse, quail, partridge and woodcock are what the 20 gauge was made for. A light 2¾ inch load with an improved cylinder or modified choke is a classic setup, and a light gun is a joy on a long walk.
Clay targets
Skeet, sporting clays and trap are all shot with 20 gauge guns, and there are competitions with separate 20 gauge classes. Light 7/8 ounce target loads keep recoil low over a hundred shells.
Waterfowl and turkey
With 3 inch steel or tungsten loads, a 20 gauge handles ducks at moderate range. For geese and long shots, the 12 gauge is better. For turkey, a 3 inch load with a tight turkey choke is a common setup.
Deer with slugs
In places where hunters must use a shotgun for deer, a 20 gauge slug gun is effective inside 100 yards. Recoil is lower than a 12 gauge slug, which helps accuracy.
Youth and new shooters
A youth model 20 gauge with light loads is a good start. Training, safe handling and a gun that fits matter more than the gauge.
20 gauge vs similar gauges
The table lists the gauges most often compared with the 20. Figures are rounded and apply to common 2¾ and 3 inch shells.
| Gauge | Bore diameter | Common shell lengths | Typical shot load | Typical use |
|---|---|---|---|---|
| 12 gauge | .729 in | 2¾, 3, 3½ in | 1 to 1⅜ oz | All-purpose |
| 16 gauge | .662 in | 2¾ in | ⅞ to 1⅛ oz | Upland birds |
| 20 gauge | .615 in | 2¾, 3 in | ¾ to 1¼ oz | Upland birds, youth, light guns |
| 28 gauge | .550 in | 2¾ in | ¾ oz | Light upland, skeet |
| .410 bore | .410 in | 2½, 3 in | ½ to ¾ oz | Small game, first guns |
Against the 12 gauge, the 20 gauge carries less shot, but a quality 1 ounce load patterns nearly as well as a 1 ounce 12 gauge load, and the gun is lighter. If you shoot geese or other large birds at long range, the 12 has the edge. Against the 28 gauge and .410, the 20 has a bigger shot charge and more choices of loads, which makes it more forgiving for beginners.
Care and storage
Clean the barrel and action after use, and wipe down the gun after wet hunts to prevent rust. Remove choke tubes now and then, clean the threads and add a little grease so they do not seize. Store shells in a cool, dry place and keep guns and ammunition locked away from children.
Safety and common mistakes
- Never mix 12 and 20 gauge shells. A 20 gauge shell slips easily into a 12 gauge chamber and can lodge in the barrel, where a 12 gauge shell fired behind it can burst the gun. Keep different gauges in separate, labeled containers, and never in the same pocket.
- Never load a shell longer than the chamber. A 3 inch shell in a 2¾ inch chamber can raise pressure dangerously. Read the barrel marking.
- Match the choke to the shot. Steel shot through a tight choke can damage a barrel unless the choke is rated for steel. Slugs need the right choke and barrel.
- Check the barrel before you shoot. A bore blocked by snow, mud or a stuck wad is dangerous.
- Keep the muzzle pointed in a safe direction, and keep your finger off the trigger until you are ready to fire.
- Know your target and what is beyond it. Shot can travel far, and birdshot can carry hundreds of yards.
- Wear eye and ear protection every time.
Frequently asked questions
What does 20 gauge mean?
The number comes from how many lead balls the size of the bore it takes to make one pound. For a 20 gauge, twenty balls weigh a pound. Smaller numbers mean larger bores.
Is a 20 gauge good enough for hunting?
Yes. With the right load and choke it handles upland birds, turkey, ducks at moderate range and deer with slugs. For large geese at long range, a 12 gauge is better.
Is a 20 gauge good for beginners and youth?
It is a good choice because the gun is lighter and the recoil is lower. Make sure the stock fits, and start with light 7/8 ounce loads.
Can I shoot 3 inch shells in a 2¾ inch chamber?
No. A shell longer than the chamber can raise pressure dangerously. Check the chamber length marked on the barrel and only use shells at or below that length.
Can a 20 gauge shell fit in a 12 gauge gun?
Yes, and that is the danger. A 20 gauge shell can slide into a 12 gauge chamber and lodge ahead of it. Never keep the two together.
What shot size should I use?
It depends on the target. Use #8 or #9 for skeet, #7½ to #8 for dove and sporting clays, #5 to #6 for pheasant and #4 to #6 for turkey.
How far can a 20 gauge shoot?
Effective range with birdshot is typically 30 to 40 yards, depending on shot size and choke. With slugs it is generally 75 to 100 yards or less.
Is a 20 gauge good for home defense?
Many people use it for that purpose because the gun is light and easy to handle. Training, safe storage and attention to what lies beyond the target matter most. Follow your local laws.
Sources
Sources reviewed · 29 October 2026