Virginia Gun Owners Forum - VGOF

The short answer is because they are different cartridges in ways that matter.

Of course .22M is much longer, but there are some key differences. The case head of the .22M in several measurements is larger than .22LR. If you put a .22LR into a .22M chamber it wiggles around because the OD of the brass is smaller and the rim is also different. There are other things like a .22LR bullet is kind of mushroomed shaped so that the OD of the bullet and the brass are flush which is unlike most other rounds, including the .22M, where the brass OD is larger than the bullets. Etc.

In a pinch it probably could work, but it isn't advisable. There are guns like this one where they provide a second cylinder so you can shoot either round: http://www.ruger.com/products/newModelS ... odels.html

The chambers are different in ways that matter so you can't do a .357Mag/.38Sp swap.

It's not just a difference in case length. The .22 Mag has a significant taper to the case not present in the .22 LR. You can easily visually compare the difference between the base and rim diameters of the two cartridges with the .22 Mag being noticeably larger.

Firing a .22 LR in a .22Mag chamber often results in a split case. It will almost surely result in a wimpy bullet velocity.

Yeah, if you want to shoot something smaller and weaker in your .22mag, you have .22WRF.

You can shoot .22LR in a .22WMR, but you may have some ignition issues, and the case will split. Sort of like shooting .32SWL in a Nagant revolver. It's not a great idea.

The .22 WMR is based on the .22 Winchester Rimfire cartridge, which is different from the .22 Long Rifle, Long, and Short cartridge. The ammo companies stopped making the .22 Winchester Rimfire due to the popularity of the other cartridge. Someone started making the .22 Winchester Rimfire a few years ago, but the prices per round were significantly higher than the LR.

Jim