rimfirekalibers

Rimfire calibers are a class of firearm cartridges in which the primer material is formed into the rim of the cartridge case rather than in a separate primer cup. When struck by the firing pin, the primer in the rim ignites the powder charge, which then drives the bullet. Because ignition occurs in the rim, rimfire ammunition generally uses smaller cases with lower powder capacity, and it is more sensitive to chamber cleanliness and firing-pin condition than centerfire ammunition.

The most common rimfire caliber is the .22 Long Rifle (LR), widely used for target shooting, plinking, and training. Other traditional rimfires include the .22 Short and .22 Long, which remain in use for specialized applications and historical firearms. In addition, modern rimfire options include the .22 Winchester Magnum Rimfire (WMR), a higher-velocity cartridge, and the .17 HMR (Hornady Magnum Rimfire), a necked-down variant designed for higher velocity and varmint pursuit. There are also niche and older rimfires such as the .22 CB Cap or .22 BB Cap, which are largely historical or specialized.

Rimfires offer low recoil, low cost, and generally good reliability in well-maintained firearms, making them popular for beginners, training, and casual shooting. However, their lower pressure and energy limit hunting applicability to small game and pests, and ignition or feeding problems can occur more readily in dirty or damaged rims. Each rimfire caliber typically requires a firearm chambered specifically for that cartridge, and compatibility is essential to safe and reliable operation.

Historically, rimfire technology emerged in the 19th century, with early rimfire designs giving way to the modern, widely used .22 LR in the late 1800s. Subsequent rimfire developments expanded velocity and variety, resulting in the current family of .22 LR, .22 WMR, .17 HMR, and related variants.