New hunters often tell me that cartridge nomenclature is the most confusing thing about firearms. Two questions usually top their list: what is a shotgun “gauge,” and what’s the difference between a “12 gauge” and a “20 gauge?”
If you’ve found yourself asking these questions–or wondering why larger gauges use smaller numbers, which gauge is best for waterfowl, or how shotguns are like pirate cannons–you’ve come to the right place.
What Are Shotgun Gauges?
When we talk about a rifle or pistol “caliber,” we’re describing the interior, or “bore,” diameter of a gun barrel and the diameter of the projectile that can be fired through that bore. A 9mm Luger bullet is 9mm wide, for example, and can be fired down a 9mm bore. There are exceptions to this general rule, but that’s the gist.
In a similar way, a shotgun “gauge” describes the width of the bore, but it uses a different measuring stick to do it. Technically speaking, a shotgun gauge is defined as “the weight of a solid ball of lead that might fit perfectly in the bore of a shotgun expressed as the inverse of said ball’s weight as a fraction of a pound.”
That sounds more confusing than it is. For example, a sphere of lead that fits perfectly in a 12-gauge shotgun bore weighs 1/12th of a pound. The sphere of lead that fits perfectly in a 20-gauge shotgun weighs 1/20th of a pound, and so on. You can also think of this another way: how many lead balls of the shotgun bore’s diameter does it take to equal one pound? The answer is the shotgun’s gauge.
This measuring system comes from the days when a cannon might shoot a lead ball weighing eight pounds and so was called an “eight-pounder.” You could call your 12-gauge shotgun a “1/12th pounder,” but you’d have to wear an eye patch and own a parrot to do it.
Since larger lead balls weigh more than smaller lead balls, they take up a larger fraction of a pound. That’s why 12-gauge shotguns have a larger bore than 20-gauge shotguns, and 20-gauge shotguns have a larger bore than 28-gauge shotguns.
The most common exception to this rule is the .410 bore. The inventor of the .410 was apparently tired of the gauge system, and so adopted the easier-to-understand caliber system. A .410 shotgun’s diameter is simply 0.41 inches. For those curious, the lead ball that fits perfectly in a .410 bore weighs about 1/67th of a pound, making the .410 a 67-gauge shotgun.
Shotgun Gauge Options
You could theoretically make a shotgun in any gauge, but manufacturers have settled on six options:
- 10 gauge (.775 inches)
- 12 gauge (.729 inches)
- 16 gauge (.685 inches)
- 20 gauge (.615 inches)
- 28 gauge (.550 inches)
- .410 (.410 inches)
You can find shotguns in other gauges (24 and 32, for example), but these are far less common.
Most hunters know from experience that 12 gauge and 20 gauge are the most popular, and that experience is borne out at the gun counter. Midway USA, one of the largest online ammunition dealers, offers 487 12-gauge options and 157 20-gauge options. The next three spots are filled by .410, 28 gauge, and 16 gauge, respectively, but they each have one-third as many options available as 20 gauge.
The specific historical reasons for the popularity of these two gauges are beyond the scope of this article, but it’s easy to understand why they remain popular today. Both can be used for a wide array of applications, including hunting, target shooting, and home defense. Both are widely available from a variety of manufacturers, and both can be found chambered in shotguns from every major gun company.
Either gauge can perform effectively in almost any hunting scenario, but each comes with its own costs and benefits. Here’s how they break down in terms of ballistics, shootability, and versatility.
12 GA vs. 20 GA: Ballistics
A 12-gauge shotgun holds a power advantage over a 20-gauge, but unlike most cartridge comparisons, faster projectiles aren’t the cause.
It’s a common misperception that a 20 gauge is less powerful than a 12 gauge because it shoots pellets more slowly. Generally speaking, that’s not the case. While a 12 gauge can be loaded to higher velocities at the top end, most 20-gauge shells push pellets just as fast as most 12-gauge shells. The difference is that a 12 gauge can fit more and sometimes larger pellets in its shell.
A 12-gauge shell can be loaded with between 5/8 ounces and 2 ½ ounces of lead shot, and most loads fly between 1,200 and 1,500 feet-per-second. Federal, for example, offers a 2 ½ ounce TSS turkey load, a deer hunting shell loaded with ten #000 buckshot pellets (the largest buckshot available), and a variety of Black Cloud waterfowl options with up to 1 ½ ounces of payload. It’s safe to say that if you opt for a 12 gauge, you’ll have more than enough power to get the job done in virtually any hunting scenario.
Twenty-gauge shells have a smaller diameter, so they can’t hold as many pellets as their 12-gauge cousin. The heaviest shot payload Federal offers is 1 5/8 ounces, #2 buck is the largest buckshot available, and the Black Cloud payloads top out at 1 ounce. The pellets are traveling at similar velocities, but since there are fewer of them, the shot pattern is smaller, and animals are more difficult to hit.
Of course, “difficult” is not “impossible.” A 20 gauge can do everything a 12 gauge can do. You can hunt deer, waterfowl, upland birds, and turkeys with a 20 gauge—you just have to be more practiced to do it.
Overall, however, the 12’s larger capacity gives it the clear edge in this category.
Winner: 12 Gauge
12 GA vs. 20 GA: Shootability
The popularity of the 12 gauge can be explained by its ability to walk the line between powerful and painful-to-shoot. Larger-gauge shotguns can throw more lead down range, but for most folks, those guns are too heavy, and the recoil is too painful. Twelve-gauge shells have bruised many a shoulder, but with practice and a shotgun that fits, it can be shot all day without much discomfort.
But it’s tough to compete with the 20 gauge when it comes to shootability. Recoil is lighter in hunting shells thanks to the smaller payloads, and 20-gauge shotguns can be designed to be lighter and more packable. Weatherby’s 12-gauge Element Waterfowler, for example, weighs 6.75 pounds while the 20-gauge version of the same gun weighs 6.25 pounds. You’ll save 0.8 pounds going with the 20-gauge Orion-I, and a full pound in the 18i Deluxe.
The cost of shells is comparable, but a 20-gauge shotgun is usually going to be more “shootable” than a 12 gauge.
Winner: 20 Gauge
12 GA vs. 20 GA: Versatility
Versatility is any shotgun’s true strength. The ability to go after large game, small game, and birds with a single gun is why hunters keep coming back to their faithful smoothbores. No matter how many new high-speed-low-drag rifle cartridges hit the market, there will always be a place for a shotgun in every gun safe.
But which of our two most popular shotgun gauges is more versatile?
I’ll spoil the ending and tell you it’s the 12 gauge. The 12’s larger diameter means you can shoot whitetail with larger slugs and buckshot for more reliable kills. It offers a wider shot spread for upland birds, better patterns for waterfowl, and heavier pellets for turkeys. The 20 gauge can target all these species, but the 12 gauge can do it better.
Why, then, does anyone choose to shoot a 20-gauge shotgun? In any scenario in which weight and recoil matter more than power, the 20-gauge will be more “versatile” because the person behind the trigger will be more effective.
For upland hunters who carry their shotguns over long distances, a 20 gauge might be the way to go. Plus, the close-range nature of most upland bird shots mitigates the 12’s power advantage, and the lighter recoil on the 20 never hurt anyone’s accuracy. Federal’s TSS loads have also closed the gap in the turkey woods, which makes the 20 a great option for the young or recoil-sensitive hunter.
Still, the 12’s ballistic advantage allows it to target these species and more with greater efficacy. It gets the nod in this category as well.
Winner: 12 Gauge
Last Shot
You may have noticed the frequent use of sissy words like “usually,” “might,” and “generally speaking” in this article. I don’t recommend these qualifying words for powerful prose, but this topic requires them. The wonderful world of scattergun shooting is as varied and complicated as the animals we hunt, and the sheer variety of shell options means that almost any statement can be discounted with a counterexample.
That’s inconvenient for me, but it’s great for you. It means you can find lightweight 12-gauge guns for long treks through upland territory. It means you can buy hard-hitting 20-gauge loads for waterfowling, and recoil-eliminating 12-gauge loads for long days at the sporting clay course. Whatever you want to do, you’ll be able to find an effective load in either 12 or 20 gauge, which is the real beauty of shotguns.
But, generally speaking, the larger 12 gauge offers more power and versatility while the smaller 20 gauge offers better shootability. As the winner of two of the three categories, the overall winner has to be the most popular sporting shell of all time.
Overall Winner: 12 Gauge
