Which of the following is NOT a classification of shotguns?

The classification of shotguns is generally categorized based on their mechanisms of operation or design. Single-shot single barrel, pump action, and semiautomatic are well-established categories.

Single-shot single barrel shotguns are designed to hold only one shell at a time. They are simple in construction and often favored by beginners due to their ease of use.

Pump action shotguns operate using a sliding mechanism that requires the shooter to manually pump the fore end to eject the spent shell and chamber a new one. This type is popular for its reliability and quick follow-up shots.

Semiautomatic shotguns use gas or recoil energy to automatically cycle the action, allowing for successive shots to be fired with each pull of the trigger without needing to manually eject and chamber a new shell.

Leverage action, on the other hand, is not recognized as a standard classification for shotguns. While firearms may utilize various mechanical systems, leverage action is not a term commonly associated with shotgun designs. It generally refers to a type of mechanism seen in other firearm categories, but not one that is applied specifically to shotguns. Thus, this distinction clarifies why it does not fit among the classifications of shotguns.