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The .22 Winchester Magnum, most commonly called .22 WMR (for Winchester Magnum Rimfire) or just .22 Magnum, is a rimfire rifle cartridge. Commonly loaded with a 40 grain (2.6 g) bullet, it can deliver velocities in the 1900 ft/s (580 m/s) range from a rifle barrel.
History
The .22 WMR was introduced in the 1950s by Winchester, and it was the only successful rimfire cartridge introduced in the 20th century. The .22 WMR uses a larger case than the more popular .22 Long Rifle, both in diameter and length. The .22 WMR's case is also much thicker, allowing much higher pressures. The combination of more powder and higher pressures gives velocities over 2000 feet per second (610 m/s) from a rifle, and 1500 feet per second (460 m/s) from a handgun.
Uses
Since the .22 WMR generally uses the same weight bullets as the .22 Long Rifle, it is generally used in similar situations. The 40 grain .22 WMR at 100 yards still retains the velocity of a .22 LR at the muzzle, which can provide improved penetration at all ranges, and more reliable expansion at long range 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 medium range varmint rifle cartridge. The relatively quiet sound of firing and negligable recoil also make it a very pleasant rifle to shoot for extended periods of time. It is also significnatly less expensive to shoot than its nearest competition, the centerfire .22 Hornet and the new 5.7 x 28 mm.
Firearms using .22 WMR
The .22 WMR operates at pressures beyond what normal blowback actions typically handle, but in the 1990s semiautomatic .22 WMR rifles were introduced by Sturm, Ruger and Marlin Firearms. Before this time, most .22 WMR firearms were bolt action rifles, though the .22 WMR is also found in a number of revolvers by Taurus and Sturm, Ruger, and was previously available in semiautomatic pistols by the now defunct manufacturers AMT and Grendel. Both of these designs used specially designed chambers with flutes or gas ports, designed to lubricate the long, thin cartridge with gasses from the chamber, overcoming the Blish effect and allowing easy extraction of the cartridge.
Ammunition
While the .22 WMR is a far more powerful cartridge than the .22 Long Rifle, ammunition is not available in the incredible variety of .22 LR ammunition. Availability is also not as great as the .22 LR; while the .22 WMR is by no means hard to find, nearly every retailer that sells ammunition will carry .22 LR. The price of .22 WMR is substantially higher than almost all .22 LR ammunition, though it is significantly less expensive than ammunition in the new .17 Rimfire calibers. Since many of the rifles that chamber the .22 WMR use tubular magazines, bullet noses are generally flat or blunt to allow smooth feeding. While a pointed bullet is not going to rest against the primer of the round in front of it (like in a centerfire cartridge), a pointed bullet could still hang on the manufacturer's stamp, which is found in the middle of the base of the cartridge.
Due to the limited selection of commercial ammunition, the .22 WMR was the case used by a small but dedicated group of wildcatters for handloading high performance rimfire ammunition. Generally these loads would use more aerodymamic pointed bullets, the same type used by .22 caliber centerfire cartridges. While these bullets were often heavier than standard .22 WMR bullets, the sharp nose and tapered tail retained velocity better, and delivered more energy downrange. Other wildcatters would neck the .22 WMR down to smaller calibers, such as .20 (5 mm) and .17 (4.5 mm) or even smaller, in an attempt to get maximum velocity and the flattest possible trajectory (see external ballistics).
The .22 WMR was also the basis for the first new commercial rimfire of the 21st century, the .17 HMR. The .17 HMR, with its tiny .172 caliber (4.5 mm) bullet, offers much higher velocities and a flatter trajectory than the .22 WMR, though the .22 WMR still offers better penetration with its heavier bullet (see terminal ballistics).
Not generally thought of as a defense cartridge, for its size it is formidable. From a handgun it will generate over a 42% one shot stop ratio on human targets, according to Marshall and Sanow). From a rifle, of which many models are available, it develops muzzle energy equal to that of the subsonic 9mm Luger loadings. The new 5.7 x 28 mm SS196SR round chambered in the FN P90 personal defense weapon produces very similar ballistics to the .22 WMR rifle, firing a 40 grain bullet at 1800 f/s.
See also
References
Bibliography
External links
- Chuck Hawk's page on the .22 WMR
- The .22 WMR TODAY, Guns Magazine, June, 2001 by C. Rodney James
- Three .22 WMR Loads From Remington, Handguns Magazine, by Phil W. Johnston
- Reloading Techniques: .22 Win. Magnum Rimfire, Performance Shooter, April 1996
".22 WMR"