Which of the following is not part of a cartridge to a shotgun shell?

The component that is not part of a cartridge in a shotgun shell is the choke. A choke is a constriction at the muzzle end of a shotgun barrel that helps control the spread of the shot as it exits the barrel. It affects how tightly or loosely the shot is patterned when fired but is not actually a part of the cartridge itself.

In contrast, the wad is an essential part of a shotgun shell, serving to separate the shot from the propellant and allow for a more consistent shot pattern. The slug is also a component found in certain shotgun shells, specifically designed for shooting single projectiles instead of multiple pellets. The bullet, while a common term in reference to ammunition, specifically refers to cartridges designed for rifles or handguns, which do not apply in this context as shotguns utilize shot, slugs, or specialty loads.

Understanding these components clarifies the distinction between what comprises a shotgun shell and additional equipment used to modify its performance.