What Is 0.22 Winchester Magnum Rimfire

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Last updated: April 11, 2026

Quick Answer: The .22 Winchester Magnum Rimfire (.22 WMR) is a rimfire cartridge introduced by Winchester in 1959, designed as an enlarged and more powerful version of the .22 Winchester Rimfire. It fires 30-50 grain bullets at velocities of 1,500-2,200 feet per second and operates at a maximum pressure of 24,000 psi, making it the most powerful rimfire cartridge available for several decades.

Key Facts

Introduced in 1959 by Winchester; first rifle chambering was the Marlin Levermatic in 1959
Standard bullet weights range from 30 to 50 grains, delivering 1,500-2,200 feet per second muzzle velocity
Produces 150-325 foot-pounds of muzzle energy depending on ammunition load
Effective hunting range of approximately 125 yards with accurate shots possible to 150 yards
Was the only successful rimfire cartridge introduced in the 20th century until surpassed by .17 Winchester Super Magnum

Overview

The .22 Winchester Magnum Rimfire (.22 WMR) represents one of the most significant developments in rimfire ammunition history. Introduced by Winchester in 1959, this cartridge was engineered as an enlarged and significantly more powerful version of the earlier .22 Winchester Rimfire (.22 WRF), offering shooters a substantial performance upgrade while maintaining the convenience and affordability of rimfire ammunition. Although Winchester initially developed the cartridge, the first rifle to be commercially chambered for it was actually the Marlin Levermatic in 1959, followed by Winchester's own rifles in 1960.

The .22 WMR achieved considerable acclaim as the most powerful rimfire cartridge available for several decades, providing ballistic performance that approached some centerfire rounds while retaining the benefits of rimfire simplicity and reduced cost. This combination of power and practicality made it an instant success among hunters, target shooters, and firearms enthusiasts. The cartridge remained the dominant magnum rimfire option until the introduction of the .17 Winchester Super Magnum in 2013, which ultimately surpassed it in velocity and kinetic energy.

How It Works

The .22 WMR operates using rimfire ignition, where the firing pin strikes the cartridge rim rather than a central primer, setting off the priming compound and igniting the propellant.

Cartridge Dimensions: The .22 WMR features a maximum case length of 1.055 inches (26.8 mm) and an overall cartridge length of 1.350 inches (34.3 mm), with a rim diameter of 0.300 inches (7.62 mm) and bullet diameter of 0.224 inches (5.69 mm).
Pressure Specifications: The cartridge operates at a maximum average pressure of 24,000 psi (165 MPa), as defined by SAAMI (Sporting Arms and Ammunition Manufacturers' Institute) standards, with a headspace dimension of 0.050–0.056 inches.
Ballistic Performance: Modern factory ammunition typically features 30- to 50-grain bullets propelled to muzzle velocities of 1,500–2,200 feet per second (457–671 m/s) from a 24-inch rifle barrel, delivering between 150 and 325 foot-pounds of muzzle energy depending on the specific load and bullet weight.
Velocity Variations: The lightest commercially available 30-grain bullets achieve the highest velocities at approximately 2,200 feet per second, while heavier 50-grain bullets travel at reduced velocities of around 1,530 feet per second, allowing shooters to select ammunition tailored to their specific needs.
Trajectory Characteristics: The .22 WMR delivers a notably flat trajectory, shooting flatter and farther than the standard .22 Long Rifle at all ranges, making it superior for both precision shooting and hunting applications where bullet drop must be minimized.

Key Comparisons

Feature	.22 Winchester Magnum Rimfire	.22 Long Rifle	.17 Winchester Super Magnum
Introduced	1959	1887	2013
Typical Bullet Weight	30-50 grains	30-40 grains	15-25 grains
Muzzle Velocity	1,500-2,200 fps	900-1,300 fps	2,000-2,600 fps
Muzzle Energy	150-325 ft-lbs	75-140 ft-lbs	140-275 ft-lbs
Effective Range	125 yards	50-75 yards	150+ yards
Maximum Pressure	24,000 psi	24,000 psi	27,000 psi

Why It Matters

Varmint Hunting: The .22 WMR is highly effective for eliminating small game including rabbits, hares, groundhogs, prairie dogs, foxes, raccoons, and opossums, offering sufficient power and accuracy for humane, quick kills at hunting ranges.
Target Shooting Excellence: The cartridge's flatter trajectory, superior ballistic coefficient, and consistent performance make it the preferred choice for rimfire competitive shooting events and precision target shooting enthusiasts seeking better accuracy than .22 LR.
Ammunition Economics: While more powerful than .22 Long Rifle, the .22 WMR remains significantly more affordable than centerfire ammunition, making extended shooting sessions and practice feasible for budget-conscious shooters and hunters.
Recreational Shooting: The relatively quiet report and negligible recoil make the .22 WMR exceptionally pleasant for extended plinking and recreational shooting, reducing shooter fatigue while maintaining adequate performance for most non-hunting applications.

The .22 Winchester Magnum Rimfire continues to occupy a unique position in the ammunition market as a bridge between the ubiquitous .22 Long Rifle and more powerful centerfire cartridges. Its combination of superior ballistic performance, low recoil, minimal noise, reasonable cost, and widespread firearm availability ensures its continued relevance for hunters, competitive shooters, and recreational enthusiasts. Although newer cartridges like the .17 Winchester Super Magnum have surpassed its raw performance metrics, the .22 WMR's nearly 70-year track record and established infrastructure make it an enduring choice for anyone seeking a reliable, effective, and affordable rimfire cartridge for moderate-range applications.