The .22 WMR (.22 Magnum): Specs and Uses

The .22 Winchester Magnum Rimfire is a rimfire cartridge listed by SAAMI as 22 WMR or 22 WIN MAG, and it is also commonly called .22 Mag. If you are comparing 22 wmr with .22 LR, the key points are simple: .22 WMR is listed as a different cartridge, has different SAAMI barrel dimensions, published nominal velocities that run higher than common .22 LR listings, and it must not be substituted for .22 LR in either direction.

What .22 WMR is

The .22 Winchester Magnum Rimfire is a rimfire cartridge. Winchester explains rimfire ignition this way: when the trigger is pulled, the firing pin strikes and crushes the cartridge rim to ignite the primer. For a broader explanation of that ignition system, see our guide to rimfire vs centerfire.

SAAMI’s 2026 rimfire standard lists the cartridge name as 22 Winchester Magnum Rimfire, with 22 WMR and 22 WIN MAG as abbreviated names. SAAMI separately lists 22 Long Rifle with the abbreviation 22 LR.

American Hunter describes it as an elongated version of the older .22 WRF, or Winchester Rimfire, cartridge.

.22 WMR vs .22 LR dimensions

The easiest way to see why .22 WMR and .22 LR are not the same cartridge is to compare the SAAMI barrel dimensions shown below. The listed bore and groove dimensions are different.

SAAMI dimension	.22 LR Sporting	.22 WMR
Bore diameter	.217 inch	.219 inch
Groove diameter	.222 inch	.224 inch

Those barrel dimensions matter because the bore and groove dimensions are part of the firearm and ammunition system. The cartridges may both be “.22” rimfires in everyday language, but their SAAMI drawings are not the same.

Why .22 WMR and .22 LR are not interchangeable

Do not use .22 WMR and .22 LR as substitutes for each other. Winchester’s Model 9422 manual says the .22 Long Rifle version is not designed to handle .22 WMR cartridges. The same manual says the .22 WMR version is made to handle .22 WMR cartridges only, and warns not to use .22 Long.22 Long Rifle, or .17 HMR in a Model 9422 chambered for .22 WMR.

CCI gives the same practical warning in a different way: a .22 WMR cartridge will not fit in a .22 LR chamber, while a .22 LR cartridge can fit in a .22 WMR chamber and should not be fired there.

The safe rule is to use only the cartridge designation marked for the firearm and confirmed by the owner’s manual. For a deeper profile of the smaller cartridge, see our .22 LR guide.

SAAMI pressure and nominal velocity

SAAMI notes that .22 WMR displays higher variations than other rimfire cartridges and assigns it a 2,400 psi standard deviation.

A SAAMI table lists these .22 WMR bullet weights and nominal velocities:

Bullet weight	SAAMI listed bullet type	Nominal velocity
28 grains	JHP-NL	2,175 fps
30 grains	JHP	2,200 fps
33 grains	PT	1,950 fps
34 grains	JHP	2,075 fps
40 grains	All	1,875 fps
45 grains	LHP	1,550 fps
50 grains	JHP	1,650 fps

For comparison, SAAMI lists multiple .22 LR nominal velocities. Its .22 LR entries include 36 grain loads at 1,200, 1,260, and 1,385 fps, and 40 grain loads at 1,040, 1,080, 1,135, 1,235, 1,275, and 1,435 fps.

Published ammunition examples

Ammunition makers publish their own ballistic tables for specific loads. This example is not a recommendation, but it shows one kind of .22 WMR bullet weight and velocity listed by a major manufacturer.

Maker and catalog listing	Bullet	Muzzle	50 yards	100 yards
CCI 2026 Maxi-Mag HP	40 grain JHP	1,875 fps	1,574 fps	1,319 fps

Bullet types and what they are marketed for

The .22 WMR appears in manufacturer catalogs with several bullet styles. SAAMI’s table includes JHP, PT, LHP, and 40 grain entries grouped as “All.” Manufacturer listings for .22 WMR include hollow point, soft point, and other designs.

CCI describes its GamePoint bullet as accurate, powerful, and intended to minimize meat and hide damage.

Typical uses for .22 WMR

CCI says most .22 WMR users use it for small game hunting, varmints, foxes, and close called coyotes. Winchester’s rimfire education sheet describes target shooting, hunting, and personal defense as common rimfire uses, and gives squirrel, rabbit, and groundhogs as small game examples.

For hunters, the important practical distinction is that .22 WMR is its own cartridge with its own chambering, ammunition selection, and local rule considerations. Winchester’s rimfire education sheet tells hunters to consult local hunting regulations before going afield.

If you are comparing flat shooting rimfire options, our queued .17 HMR guide covers another cartridge often considered alongside .22 WMR. As with .22 LR and .22 WMR, the firearm’s chamber marking and manual control what ammunition can be used.

What to check before you buy or hunt

Before buying ammunition, check the exact chamber marking on the firearm, then confirm the same cartridge name in the owner’s manual. Do not rely on the general phrase “.22 rimfire.” SAAMI lists .22 LR and .22 WMR as different cartridges, and Winchester and CCI both warn against mixing them.

Before hunting, check the current regulations from the state, provincial, or territorial wildlife agency for the species, season, method of take, and ammunition rules that apply where you will be hunting. Winchester’s rimfire education material specifically tells hunters to consult local hunting regulations before going afield.