What type of ammunition utilizes a primer compound loaded within the case?

Rimfire ammunition is a specific type of cartridge design where the primer compound is located within the rim of the cartridge case. This design allows for a more compact construction and is commonly used in various firearms, particularly in .22 caliber and small-caliber firearms. When the firing pin strikes the rim, it crushes the primer compound seated in the rim, igniting the propellant and firing the bullet.

This distinct characteristic of rimfire ammunition sets it apart from other types, as most centerfire cartridges have the primer located in the center of the casing's base and require a different mechanism for ignition. This structural difference influences the types of firearms made for each ammunition type, the cost of production, and the intended use of the ammunition. The design of rimfire ammunition is particularly advantageous for smaller caliber firearms intended for target shooting, small game hunting, and training purposes.