I've inherited a 22 MRF ctg pistol and would like to fire the weapon but I'm unsure of the type of ammunition. I'm getting differing information as to whether I can use WMR ammunition which is easy to find or if I have to use MRF ammunition. The WMR ammo will chamber just fine, I'm just a bit afraid to fire it because some sites say it may create an overpressure situation. As you can probably tell I don't know much about these firearms. Any information will be greatly appreciated. Thanks

The .22 WMR was introduced in 1959 by Winchester, but was not used by Winchester until the venerable Model 61 slide rifle could be chambered for it, well into 1960.[2] By that time, Smith and Wesson and Ruger had revolvers for it, and Savage had come out with the Model 24, a .22/.410 combination rifle. It was the only successful rimfire cartridge introduced in the 20th Century.[3]
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 (.22 WRF may be fired in a .22 WMR but not vice versa). 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 (460 m) per second (460 m/s) from a handgun. A .22 WMR round will not fit into the chamber of a .22 LR firearm but is possible to chamber and fire .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 .4" before entering the barrel causing leading in the chamber.

.22 Magnum Rim Fire and .22 Winchester Magnum Rimfire are two names for the same cartridge. Some companies just don't like to use another company's name on their product.

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Science plus Art

Thanks for all the great information, but I'm still a bit confused. You said the .22 WRF may be fired in a .22 WMR but not vice versa. Then the last comment was .22 Magnum Rim Fire and .22 Winchester Magnum Rimfire are two names for the same cartridge. This leads me to believe that I can use WMR ammo in my MRF pistol (my pistol is stamped 22 M.R.F. CTG). What am I missing here. If I can't fire the WMR ammo in this pistol where can I find this older type of MRF ordnance. Once again thanks for taking the time to explain this.

WMR and MRF are the same thing. The maker of your gun used MRF to designate "Magnum Rim Fire", same shell as the WMR "Winchester Magnum Rimfire". The .22 WRF is an older, pretty much obsolete round that operates at lower pressures then the magnum shell, and can be used in a gun chambered for the magnum, just not the other way around. Sort of like shooting 38spl's in a 357.. Hope that helps.

Larry

As long a your gun is NOT a .22WRF, you should be OK shooting either .22MRF or .22WMR.

It would also be informative if you are able to identify what make and model of gun it is. That would also tell us a great deal about what it is intended to fire.

Safe shooting.

The light just came on and I see what OKFC05 was saying. I misread the WRF for MRF. This is a very nice pistol with a serial number of M69xxx and a 3 1/2 barrel. I intend to fire a CCI 22 WMR shotshell with #12 shot (52 grain) and use it for North Georgia mountain copperheads. Does anyone know if this would be effective out to about 10 feet??
Thanks to all who replied and helped.

There are others, but these are pretty typical...

Bob - you have a model 51. All you can do it test some of the shot capsules before you step on a snake and really need it. The rimfire capsules shoot #12 shot and disperse very quickly into a wide pattern where you may not accomplish your desired intention. Centerfire shot capsules work better.

Model 51 Bob. 1969 to early 1970's maybe because it has the prefix M in the serial number.

By the way what does CTG mean in the S&W Model 51 MRF CTG?

Cartridge.

Marlin was the first to offer the new 22 WMR in their Model 57 short throw lever action. Here's a early one.

You must have had to really hunt for this almost 7 year old thread. BTW, old Bob there hasn't been back since 2012 either.

BTW, welcome to these forums.

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