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 40 grains (2.6 g) delivering velocities in the 2,000 feet per second (610 m/s) range from a rifle barrel, .22 WMR has also been loaded with bullet weights of 50 grains (3.2 g) at 1,530 feet per second (470 m/s) and 30 grains (1.9 g) at 2,200 feet per second (670 m/s). The .22 WMR was introduced in 1959 by Winchester, but was not used by Winchester until the Winchester Model 61 slide rifle could be chambered for it, in 1960. By that time, Smith and Wesson and Ruger had revolvers for it, and Savage had come out with the Model 24 and since late 2012, the model 42, a more modern update than the 24, a .22/.410 rifle. It was the only successful rimfire cartridge introduced in the 20th Century.
Since the .22 WMR generally uses the same weight bullets as the .22 Long Rifle, it is used in similar situations. The 40-grain (2.6 g) .22 WMR at 100 yards (91 m) still retains the same velocity as a .22 LR at the muzzle, which can provide improved penetration at all ranges and more reliable expansion at longer ranges with expanding bullets.
If sighted in for maximum point blank range on a 3-inch (76 mm) high target, the 40-grain (2.6 g) .22 WMR can reach ranges of nearly 125 yards (114 m). This makes the .22 WMR an effective short to medium range varmint rifle cartridge. The relatively quiet report and negligible recoil also make it a very pleasant round to shoot for extended periods. The .22 WMR can take down small game such as rabbits, groundhogs, prairie dogs, foxes, racoons, and even coyotes at close range.
