rimfire

Rimfire is a type of metallic cartridge in which the priming compound is located in the rim of the case rather than in a separate primer cup. When the firing pin strikes the rim, the primer ignites and its flame travels into the main powder charge. This design generally makes rimfire ammunition cheaper to manufacture and is most commonly used in small-caliber firearms. Rimfire cases are thin, and the rim must remain intact for reliable ignition; a damaged or corroded rim can cause misfires or failure to fire. Because of these characteristics, rimfire rounds are typically associated with light sport shooting, plinking, and hunting small game.

History and development: Rimfire cartridges emerged in the 19th century. Louis Flobert is often credited with creating the first practical rimfire cartridge around 1845. The most enduring rimfire cartridge is the .22 Long Rifle, introduced in the late 19th century and widely adopted for training, target shooting, and small-game hunting. The rimfire concept is well suited to small, low-pressure rounds, while larger calibers typically use centerfire designs.

Variants and examples: Common rimfire cartridges include .22 Short, .22 Long, and the widely used .22 Long Rifle. Other rimfire options include .22 WMR (Winchester Magnum Rimfire) and the smaller .17 HMR (Hornady Magnum Rimfire). Rimfire ammunition is predominantly used in rifles, with some pistols chambered for small calibers. It is valued for low recoil, affordability, and broad availability, but generally offers lower energy and velocity compared with centerfire cartridges.