.22 Winchester Magnum Rimfire

The .22 Winchester Magnum Rimfire, also known as the .22 WMR, .22 Magnum, .22 WMRF, .22 MRF, or .22 Mag, is a rimfire cartridge. Originally loaded with a bullet weight of delivering velocities in the range from a rifle barrel, .22 WMR is now loaded with bullet weights ranging from at to at .

History

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. The first rifle to be offered in the new chambering was the Marlin Levermatic rifle in 1959, because its design was easily modified to accept the more powerful cartridge. By the time of the introduction of the Winchester 61, 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/shotgun combination gun. 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 LR, both in diameter and length. The .22 WMR case is a lengthened version of the older .22 WRF and both of these cartridges have the bullet seated within the case, instead of using a heeled bullet as in the .22 LR. In the most common modern .22 WMR loadings using a bullet, the combination of more powder and higher sustained pressures gives velocities of from a rifle and from a handgun. A .22 WMR round will not fit into the chamber of a .22 LR firearm due to the greater length and width of the case dimensions.

Although the bullet diameters are the same, the larger .22 WMR chamber does not support the smaller .22 LR cartridge. Firing the smaller .22 LR round in a .22 WMR chamber results in swollen or split cartridge cases, high-pressure gas leakage from the rear of the chamber, and bullets striking the chamber throat out of alignment, which can result in injury to the shooter or bystander and which does result in poor ammunition performance.

Gun makers offer .22 revolver models with cylinders chambered either in .22 LR or in .22 WMR and as convertible kits with both cylinders which allow the shooter to easily switch calibers on the same firearm.

Uses

Since the .22 WMR uses bullets comparable in weight to the .22 Long Rifle, but is considerably faster, it shoots flatter and farther and hits harder at all ranges. The same bullet from a .22 WMR at still has 50% more kinetic energy than .22 LR at the muzzle. The .22 WMR provides improved penetration and more reliable expansion at longer ranges with expanding bullets.

If sighted in for maximum point blank range on a high target, the .22 WMR has an effective range of nearly . This makes the .22 WMR a short to medium-range varmint rifle and hunting rifle cartridge. The .22 WMR can kill small game such as rabbits, hares, groundhogs, prairie dogs, foxes, raccoons, opossums, and coyotes.

Firearms using .22 WMR

It first appeared in the Marlin Model 57M Levermatic carbines in 1959, which was followed by the .22 WMR over .410 bore Savage Model 24 combination gun, followed by Winchester's own Model 61 and 275 pump-action rifles and Model 255 lever-action rifle. The Chiappa Double Badger combination gun also comes with a .22 WMR over .410 bore option. The Springfield Armory M6 Scout is also made in .22 Magnum over .410 bore. The Chiappa M6 Survival Gun is similar combination gun that comes with a 12 gauge or 20 gauge shotgun barrel over a .22 Magnum barrel.

A number of single-shot and repeating rifles were offered in .22 WMR. 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.

Revolvers in .22 WMR are made by Smith & Wesson, Colt, 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.

thumb|60px|.22 WMR [[snake shot]]

The Marlin Model 25MG is a smooth bore, eight-shot, magazine-fed, .22 WMR, bolt-action shotgun manufactured by Marlin Firearms. It was specifically designed to use snake shot, and marketed as a "garden gun" for use in dispatching small garden and farm pests. It has an effective range of about 15 yards when using snake shot.

.22WMR have been used in experimental machine gun design, such as the prototype Stoehr machine pistol (1960-1970).

The Argentine EDDA submachine gun uses the .22 WMR round.

In 2014 Kel-Tec released the CMR-30, a PDW-style rifle chambered in .22 WMR with a 16" barrel and a 1:14 twist rate. It uses the same double stack 30-round magazine as the PMR-30.

In 2018 Standard Manufacturing introduced an 8-round .22 WMR revolver at the Las Vegas Shot Show. The revolver was originally introduced as the Volleyfire. The gun has side-by-side barrels, and fires 2 rounds of .22 WMR (1 bullet per barrel) with every pull of the trigger. In 2019 the gun went into production and was renamed "Thunderstruck".

In recent years, a few UK companies such as Guncraft Ltd have been making semi-automatic AR-15-style rifles chambered in 22 WMR, marketed to civilian shooters who, due to the UK's restrictive gun laws, do not have access to self-loading center-fire rifles.

Ammunition

thumb|From the left, [[.22 Short, .22 LR, .22 Winchester Magnum Rimfire, and .22 Hornet]]

The .22 WMR is an enlarged, more powerful version of the much earlier .22 WRF.

The .22 WMR was for a time the most powerful rimfire round available; 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 polymer plastic ballistic tips that reduce the hazards of pointed ammunition in tubular magazines.

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).

The limited selection of commercial ammunition for the .22 WMR has inspired specialist wildcatters to select the .22 WMR case for handloading high performance rimfire ammunition. Generally they load the wildcat cartridges with pointed bullets for the aerodynamic advantages, using the same bullets as those in .22 caliber centerfire cartridges. Though such bullets are generally heavier than standard .22 WMR, the sharp nose and tapered tail conserve energy better, delivering greater impact at longer ranges.

Other wildcatters 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 such an experimental design is the Swedish 4.5×26mm MKR.

References

External links

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