What are the two types of primers used in modern cartridges?

The two types of primers used in modern cartridges are centerfire and rimfire.

Centerfire primers are located in the center of the cartridge base and are used in most modern ammunition types. They consist of a small metal cup that contains a sensitive explosive compound. When struck by the firing pin of a firearm, the primer ignites, and this ignition helps to ignite the gunpowder in the cartridge, leading to the discharge of the bullet.

Rimfire primers, on the other hand, are located in the rim of the cartridge case. This design allows for simpler and generally less expensive ammunition, commonly used for smaller caliber firearms like .22 caliber cartridges. The design requires the cartridge case to be made of thinner material since the firing mechanism relies on the deformation of the rim to activate the primer.

Other options provided refer to different aspects of firearms that do not relate to primers. Single-action and double-action describe types of firearm actions, while revolver and semi-automatic differentiate types of firearm mechanisms. Shotgun and rifle refer to different types of firearms rather than the primers used in ammunition. Understanding these distinctions is essential for grasping the basics of firearm operation and ammunition design.