.22 Winchester Magnum Rimfire
|.22 Winchester Magnum Rimfire|
.22 Winchester Magnum Rimfire
|Place of origin||United States|
|Parent case||.22 WRF|
|Bullet diameter||.224 in (5.7 mm)|
|Neck diameter||.242 in (6.1 mm)|
|Base diameter||.242 in (6.1 mm)|
|Rim diameter||.294 in (7.5 mm)|
|Rim thickness||.050 in (1.3 mm)|
|Case length||1.055 in (26.8 mm)|
|Overall length||1.350 in (34.3 mm)|
|Test barrel length: 24 inches (610 mm)
Source(s): Cartridges of the World 
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 1,750 feet per second (530 m/s) and 30 grains (1.9 g) at 2,250 feet per second (690 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.
Dimensions & 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 (610 m/s) from a rifle using a 30-grain (1.9 g) bullet, and 1,500 feet per second (460 m/s) from a handgun. A .22 WMR round will not fit into the chamber of a .22 LR firearm, but it is possible to chamber .22 LR rounds in a .22 WMR firearm. This is potentially hazardous due to the difference in case diameter. When fired, the .22 LR case expands in the chamber, which can cause the case to split open or become stuck. Also, the long rifle bullet will travel in the magnum chamber unsupported for 0.4" before entering the barrel, causing leading in the chamber.
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.
Firearms using .22 WMR
It first appeared in the Savage Model 24 combination rifle, followed by Winchester's own Model 61 pump action rifle. A number of single-shots and repeaters were offered in .22WMR. The .22 WMR operates at pressures beyond what normal blowback actions typically handle, but the self-loading Jefferson Model 159 was introduced for the cartridge. Until the 1990s, most .22 WMR firearms were bolt action rifles. In 1977-1985 Harrington and Richardson made the first American-made semi-automatic .22 WMR. In the 1990s semi-automatic .22 WMR rifles were also introduced by Sturm Ruger and Marlin, and are currently produced by Remington and Tanfoglio Appeal Rifle as well as the Excel Arms Accelerator Rilfe.
Revolvers in .22 WMR are made by Smith & Wesson, Taurus, North American Arms, Heritage Arms, and Sturm Ruger. Semi-automatic pistols for this cartridge are (or were) produced by Kel-Tec, Grendel and AMT, the latter two now defunct (AMT has been since resurrected by High Standard).  The Grendel, AMT and Kel-Tec designs used specially designed chambers with flutes or gas ports, designed to lubricate the long, thin cartridge with gases from the chamber, overcoming the Blish effect and allowing easy extraction of the cartridge. High-Standard produced various models and versions of their classic two-shot over/under derringer in both .22 WMR and .22 LR.
The .22WMR is an enlarged, more powerful version of the much earlier .22 WRF, which is not, as commonly stated, usable in any firearm chambered for any other round, including .22WMR. The case lengths are different, and "just because it fits" is not a good reason to do it. It was for a time the most powerful rimfire round available, and even outperformed the .22 WCF.
While more powerful than the .22 Long Rifle, ammunition is not available in as large a variety as .22 LR. Availability is also not as great, either; 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, though it is less expensive than 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. Recently, new bullets have emerged from Remington, CCI, and Hornady and have 30 or 33-grain (2.1 g) polymer plastic ballistic tips.
While a pointed bullet is not going to rest against the primer of the round in front of it (as 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.
Bullets for the .22 WMR are generally unlubricated lead with heavy copper plating, in either solid nose or hollow point style designed for small game hunting or pest control (varmint hunting).
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 aerodynamic pointed bullets, the same type used by .22 caliber centerfire cartridges. While 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. An example of which is the Swedish studied 4.5×26mm MKR.
The .22 WMR is effective out to 125 yd (115 m) on varmints such as fox or coyote. When loaded with hollow-point bullets, it is too destructive for small game (under 50 yd [45 m]), such as rabbits or prairie dogs or anything intended for eating.
- Cartridges of the World 11th Edition, Book by Frank C. Barnes, Edited by Stan Skinner, Gun Digest Books, 2006, ISBN 978-0-89689-297-2 pp. 490, 492
- Barnes 1972, p.275, ".22 Winchester Magnum Rimfire".
- Frank C. Barnes, ed. Stan Skinner. Cartridges of the World, 10th Ed. Krause Publications. ISBN 978-0-87349-605-6.
- "Ruger 10/22 Magnum Serial Number History". Product History. Sturm, Ruger & Co., Inc. Retrieved 25 March 2013.
- "Autoloading Rimfire Rifle - Model 597". Remington Guns. Remington Arms Company, LLC. Retrieved 25 March 2013.
- Slowik, Max (18 January 2012). "EAA's Latest Appeal: .22 Long Rifle and .22 Magnum Bullpup Carbines". Blog. Guns.com. Retrieved 25 March 2013.
- CTD Mike (8 March 2012). "EAA to Import New .22 Tangfolio "Appeal" Bullpup Carbine". The Shooters Log. Cheaper Than Dirt. Retrieved 25 March 2013.
- "Taurus Revolver Manual" (PDF). Safety and Operation Manual. Taurus International. 25 February 2003. Retrieved 25 March 2013.
- B. Gil Horman (24 March 2011). "North American Arms Mini Revolvers". American Rifleman. Retrieved 25 March 2013. "The .22 Mag. models can be fitted with a second cylinder chambered in .22 Long Rifle, which makes practice and plinking inexpensive indeed."
- "Smith & Wesson Air Lite 351PD (.22 Magnum)". Kansas Carry. Custom Digital Services, LLC. 2010. Retrieved 25 March 2013.
- NRA Staff (22 April 2011). "Heritage Mfg. Rough Rider Revolvers". American Rifleman. Retrieved 25 March 2013. "Chambered in .22 Long Rifle and .22 WMR, Heritage Mfg.’s nine-shot Rough Rider revolvers are now available in blued, black satin, silver satin and color case-hardened-style finishes."
- Quinn, Jeff (5 January 2013). "Lightweight, Compact Ruger LCR 22 Magnum Pocket Revolver". GUNBlast.com. Retrieved 25 March 2013. "I am glad that Ruger is including the 22 magnum along with the 22 LR, 38 Special Plus P, and 357 magnum chamberings in this handy little revolver."
- B. Gil Horman (15 February 2011). "The Kel-Tec PMR-30". American Rifleman. Retrieved 25 March 2013. "As a fan of the .22 Mag. cartridge, I am very pleased that Kel-Tec built a lightweight, high-capacity semi-auto that shows off what this neat little cartridge can do."
- Eger, Chris (7 March 2013). "The Grendel Pistols: The forgotten polymers (and the birth of Kel-tec)". Guns.com. Retrieved 25 March 2013. "With the use of polymers, the weight of this target pistol was kept down to 26 ounces when loaded with an impressive array of 30-rounds of rimfire magnums."
- Kelly, Paco (9 August 2006). "Still Holding On: AMT's AutoMag II .22 Magnum Rimfire Auto". GUNBlast.com. Retrieved 25 March 2013. "It wasn't very long ago that some very well-designed little .22 Magnum handguns were available from AMT (Arcadia Machine & Tool) of Irwindale, CA."
- Quinn, Jeff (27 November 2006). "High Standard Brings Back the AMT Automag II .22 Magnum Pistol". GUNBlast.com. Retrieved 25 March 2013. "After being out of production for several years, High Standard Manufacturing is now producing the Automag II pistol that was previously produced by AMT in Irwindale, California and Galena Industries in Sturgis, South Dakota."
- "AMT AutoMag". Archived from the original on June 16, 2009.
- "High Standard Derringer". Guns in Movies, TV and Video Games. Internet Movie Firearms Database. Retrieved 25 March 2013.
- Barnes 1972, p.275, ".22 Winchester Rimfire (WRF)"
- Barnes, p.275, ".22 Winchester Magnum Rimfire".
- Barnes 1972, p.275, ".22 Winchester Magnum Rimfire".
- Sparano, Vin (2000). The Complete Outdoors Encyclopedia. New York: St. Martin's Press. ISBN 978-0-312-26722-3.
- "Remington Magnum Rimfire: 22 Win Mag PR22M1 33-grain AccuTip-V". Remington Arms Company, Inc. Archived from the original on 2008-05-30. Retrieved 2008-06-17.
- "CCI: Varmint 0073 22 Magnum RF V-MAX 30-grain poly-tip". CCI. Archived from the original on 16 May 2008. Retrieved 2008-06-17.
- "Hornady: 22 WMR 30-grain V-MAX". Hornady Manufacturing, Inc. Retrieved 2008-06-17.
- Barnes, Frank C., ed. by John T. Amber. ".22 Winchester Magnum Rimfire", in Cartridges of the World, pp. 275. Northfield, IL: DBI Books, 1972. ISBN 978-0-695-80326-1.
- Cartridges of the World 11th Edition, Book by Frank C. Barnes, Edited by Stan Skinner, Gun Digest Books, 2006, ISBN 978-0-89689-297-2 p. 479
|Wikimedia Commons has media related to .22 WMR.|
- Chuck Hawks' page on the .22 WMR
- Chuck Hawks on .22 WMR ammunition selection
- 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