The three basic chokes for a shotgun are full (tight constriction and delivers a narrow, dense spread) , modified (less constriction and delivers a medium-width spread) and improved cylinder (even less constriction and delivers a wide, open spread). A gun with no choke is called a cylinder bore and delivers the widest spread. There are also a number of specialty chokes that provide narrower or wider spreads—these are typically used for skeet shooting and turkey hunting.
A shotgun's choke also determines its effective range. The tighter the constriction, the further the effective range. For instance, a full choke is most effective at 40 to 50 yards. An improved cylinder is most effective from 20 to 35 yards. Shotgun barrels come with either fixed (non-removable) chokes or today's more popular interchangeable screw-in choke tubes that let hunters quickly and easily change chokes to match changing shooting conditions.
SUPER-FULL AND EXTRA-FULL
Case (a.k.a. Hull)
The modern shotshell case is similar to the case on a rifle or pistol cartridge. The hull is normally made from plastic, paper or, in rare cases, brass. It will also have a steel or brass head and rim attached. The case is designed to contain the powder charge, primer, wad and shot. Hulls are available in a variety of lengths such as 2.75”, 3”, 3.5”. The length of the hull refers to the overall length when the shotshell is fired.
MODIFIED
Powder
The term for any chemical compound, normally gunpowder, used to propel the bullet out of the barrel when ignited by a struck primer. Powder is commonly found in two varieties, smokeless and black. Smokeless powder is found in modern ammunition and has a significantly reduced smoke signature. Black powder on the other hand is very smoky and can be corrosive.
IMPROVED CYLINDER
Shot
The shot is the collection of small pellets that act as the projectile in a shotshell. They are commonly made of lead, steel or bismuth. The size of shot varies depending on application.
CYLINDER BORE
Primer
The primer is the small circle on the base of the shotshell. The Primer is made up of the anvil, primer cap and priming compound. When the primer is struck by the firing pin it ignites the powder contained inside the case.
SKEET CHOKE
Crimp
This is how the shot is retained in the case. There are two main types of crimps: roll and folded. The folded type of crimp is the most common on shotshells. Some roll type crimps will decrease capacity of your shotgun due to the extended length of the crimp.