The main difference between centerfire and rimfire ammunition lies in the location and type of primer used to ignite the gunpowder inside the cartridge:
- Rimfire ammunition has the primer compound contained within the rim of the cartridge casing. When the firing pin strikes the rim, it crushes it, igniting the primer and subsequently the powder. This design limits rimfire cartridges to low-pressure loads and generally smaller calibers (typically .22 caliber or less). Rimfire cases are thinner and not reloadable due to their construction
- Centerfire ammunition has a primer located in the center of the cartridge base, usually as a separate, replaceable component seated in a primer pocket. The firing pin strikes this central primer to ignite the powder. Centerfire cartridges can handle higher pressures, come in a wider range of calibers (from small handgun rounds to large rifle and shotgun shells), and are reloadable
In summary, rimfire ammo ignites via the cartridge rim and is limited to smaller, lower-pressure rounds that are not reloadable, while centerfire ammo ignites via a central primer, supports higher pressures and calibers, and is reloadable
