.17 HMR

.17 Hornady Magnum Rimfire, commonly known as the .17 HMR, is a rimfire rifle cartridge developed by the ammunition company Hornady in 2002. It descended from the .22 Magnum by necking down the .22 Magnum case to take a .17 caliber (4.5 mm) bullet, and it is more costly to shoot than traditional .22 caliber rimfire cartridges. Commonly loaded with a 17 grain (1.1 g) bullet, it can deliver muzzle velocities in excess of 2550 ft/s (775 m/s).