Shotguns are shoulder fired, smooth-bore firearms that fire shells filled with round balls of lead, steel or bismuth shot. Because the barrel walls lack rifling grooves, and that it fires multiple small projectiles, the shot pattern scatters as it exits the barrel. To control the expansion of the shot pattern, and hold it in a tighter formation downrange, many shotgun barrels have a reduced bore diameter near the muzzle. This reduced bore "chokes" the shot group together enabling it to travel farther and increase the chances of striking a target or game animal. There are five chokes used on shotgun barrels.
Extra Full Choke
An extra full choke barrel is one capable of delivering 70 percent of the shot at a distance of 45 yards. Extra full choke barrels are useful when hunting larger game birds such as wild turkeys, or Canada geese. Police riot guns and the shotguns employed by the U.S. Army are also equipped with extra full choke barrels.
Full choke shotgun barrels are those capable of delivering 70 percent of the shot pattern at a distance of 40 yards. A shotgun with a full choke barrel is often used when hunting larger waterfowl like mallard ducks, snow geese, or lesser Canada geese. In smaller bore shotguns such as .410 gauge, full choke barrels are used when hunting squirrels.
A modified choke shotgun barrel is one capable of delivering 70 percent of the shot pattern at a distance of 35 yards. Hunters often use modified choke barrels when hunting smaller game such as quail, doves, pheasants, rabbits, or smaller ducks, such as teal or bufflehead ducks.
Improved Cylinder Choke
A shotgun equipped with an improved cylinder choke barrel is capable of delivering 70 percent of the shot pattern at a distance of 30 yards. Hunters also use this type of barrel when hunting small game such as woodcock, rabbits, or varmints such as woodchucks.
A shotgun equipped with a cylinder choke barrel is capable of delivering 70 percent of the shot pattern at a distance of 25 yards. Competitive skeet shooters often use shotguns with cylinder choke barrels. Hunters may also employ them when hunting small game.
For added flexibility, many shotguns are equipped with a partially threaded barrel, allowing them to accept screw-in threaded choke tubes. The tubes allow the gunner to change his choke pattern depending on the type of game being pursued, and the diameter of the shot they are using. The tubes are available for a variety of shotgun gauges such as 12, 16, 20 and .410. Many shotgun makers such as Mossberg, Browning, Baretta, Binelli, Remington and Savage manufacture choke tubes. Some choke tubes are interchangeable between guns of different manufacture.
- less lethal shotgun and shells. image by Kevin Chesson from Fotolia.com