|This article may need to be rewritten entirely to comply with Wikipedia's quality standards. (January 2010)|
|Place of origin||United States|
|Variants||2½", 2¾", 3"|
|Shoulder diameter||.673 in (17.1 mm)|
|Base diameter||.692 in (17.6 mm)|
|Rim diameter||.761 in (19.3 mm)|
|Rim thickness||.050 in (1.3 mm)|
|Case length||2.270 (unfired, Federal ammo)|
The 20-gauge shotgun is a type of smoothbore shotgun shell that is smaller in caliber (.615) than a 12 gauge (.729). It is often used as a beginning shooter's practice round and is noted by its yellow hull.
It takes 20 lead balls of the diameter of a 20-gauge shotgun bore to equal one pound, while it only takes 12 lead balls of the diameter of a 12-gauge shotgun bore to equal the same amount. A 20-gauge shotgun is sometimes considered more suitable for hunting certain types of game, because it damages less meat, which makes it suitable for most game birds.
The 20-gauge shell is the only shell with a mandated color: yellow. This is to make 12 and 20ga shells easily distinguishable and to reduce the risk of damaging the firearm or unintentionally harming another individual.
This is because a 20-gauge shell will typically fit into the barrel of a 12 gauge, allowing a 12 gauge to be chambered behind it, leading to a dangerous barrel obstruction condition.
20-gauge shotguns are especially suitable for hunting game birds such as quail, grouse, turkey, and other small game when using shot shells. A 20-gauge can also shoot slugs and thereby become an effective deer-hunting gun. 20-gauge shotguns loaded with slugs are usually less accurate than rifles, but they often have better stopping power at short range—although this depends on the amount of gunpowder in the shell's load.
Typical game and uses
The 20-gauge is commonly used for hunting squirrels, rabbits, upland birds and waterfowl. With slugs it may be used for deer or other medium game. In addition to this, many sport shooters will participate with the 20-gauge at sporting events such as skeet and trap tournaments.
The 20-gauge is also used for security, law enforcement and personal defense purposes, generally loaded with buckshot, though the 12-gauge is usually more common for these purposes.
In addition, 20-gauge shotguns often have less recoil than 10, 12 or 16-gauge versions on average, and may be more desirable to those who want to experience less recoil for prolonged shooting. The lower recoil also makes a 20-gauge appropriate for younger (or conversely, elderly) shooters who may have a difficult time firing a larger shotgun. However, recoil is largely dependent on the weight of the gun itself; for instance, a 4.5 pound 20-gauge can have more recoil than an eight-pound 12-gauge. This is widely considered a flaw in the design of so-called 'youth' guns.