The .22 Winchester Magnum Rimfire, more commonly called .22 WMR, .22 Magnum, or simply .22 Mag, is a rimfire cartridge. Originally loaded with a bullet weight of grains ( g) delivering velocities in the feet per second ( m/s) range from a rifle barrel, .22 WMR has also been loaded with bullet weights of grains ( g) at feet per second ( m/s) and grains ( g) at feet per second ( m/s).