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 delivering velocities in the 2,000 feet per second range from a rifle barrel, .22 WMR has also been loaded with bullet weights of 50 grains at 1,750 feet per second and 30 grains at 2,250 feet per second. More recently, a high-quality 30gr Vmax cartridge from Hornady has been released. This exceeds 2200fps in a rifle and has a reputation for much greater consistency and accuracy than was previously attributed to this calibre. Accuracy around 1 MOA is achievable and this has led to this cartridge regaining ground previously lost to the excellent .17 HMR, especially as the 30gr bullet weight (nearly double that of the HMR's normal 17gr) gives it a reputation for hitting harder on larger varmints such as fox and coyote.
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 & 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.
DIMENSIONS and LOADING
The .22 WMR uses a larger case than the more popular .22 Long Rifle, both in diameter and length. The .22 WMR case is a lengthened version of the older .22 WRF. The .22 WMR's case is thicker than that of the .22 LR, allowing higher pressures. The combination of more powder and higher pressures gives velocities over 2,000 feet per second from a rifle using a 30-grain bullet, and 1,500 feet per second from a handgun. A .22 WMR round will not fit into the chamber of a .22 LR firearm, but it is possible, though unsafe, to chamber .22 LR rounds in a .22 WMR firearm, although doing so can result in injury from a leaking undersized case.
Since the .22 WMR generally uses the same weight bullets as the .22 Long Rifle, it is used in similar situations. The 40-grain .22 WMR at 100 yards 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 high target, the 40-grain .22 WMR can reach ranges of nearly 125 yards. 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, raccoons, and even coyotes at close range.
The .22 WMR is an enlarged, more powerful version of the much earlier .22 WRF. Despite frequent claims to the contrary, it should not be used in any firearm except those specifically chambered for .22 WMR. Even firearms chambered for the .22 WRF are not suitable; for one thing, the case lengths are different, and the fact that the cartridge fits into the chamber does not guarantee that using the wrong cartridge is either safe or effective.
The .22 WMR was for a time the most powerful rimfire round available, it even outperformed the .22 WCF.
Though the .22 WMR is more powerful than the .22 Long Rifle, .22 WMR ammunition is not manufactured in as large a variety as .22 LR. It also is not as widely available in retail stores. Although .22 WMR ammunition is not necessarily hard to find, nearly every ammunition retailer stocks .22 LR, whereas many do not stock .22 WMR. Furthermore .22 WMR is so much more expensive than almost all .22 LR that its price becomes a significant consideration where large volumes of ammunition are consumed.
Because many of the rifles that are chambered for the .22 WMR have tubular magazines, the bullet noses generally are flat or at least blunt to allow smooth feeding and reduce damage to the bullet. Although a pointed bullet in a rimfire cartridge will not contact the primer of the round in front of it (which is a hazard with centerfire cartridges in a tubular magazine), the manufacturer's stamp is in the middle of the base of a rimfire cartridge, and this may interfere with pointed metal bullets in a tube. However, Remington, CCI, and Hornady now produce bullet designs with 30 or 33-grain polymer plastic ballistic tips that reduce the hazards of pointed ammunition in tubular magazines