What is the name of a bullet that features a primer and an explosive charge in the base of its casing?

The bullet that contains a primer and an explosive charge in the base of its casing is referred to as a centerfire primer. In centerfire ammunition, the primer is located at the center of the cartridge base, allowing for a more reliable ignition of the gunpowder, which ultimately propels the bullet forward when fired. This design contrasts with rimfire cartridges, where the primer is built into the rim of the casing.

Centerfire primers are commonly found in a variety of modern firearms, providing advantages in terms of performance and reloading capabilities compared to rimfire ammunition. While shotgun shells do have an explosive charge and a primer, they are categorized as shotshells specifically designed for shotguns, making them a different type of ammunition altogether. Therefore, the correct identification of centerfire primer aligns with its distinct position and functionality in firearm ammunition usage.