I have heard of the 22 WMR and and am familar with it. I have never heard of the 22 RF MAGNUM, is it and the 22 WMR the same thing? Are they interchangable? Also any one heard of any auto loading 22 WMR handguns?

AMT made an autoloader in that caliber but they are out of business. They can still be found on Gunbrokers.

WMR stands for "Winchester Magnum Rimfire". People commonly refer to the cartridge as simply the ".22 Magnum". It is also called the ".22 Rimfire Magnum" and other similar designations, but all are refering to the same cartridge.

Some people confuse it with the much older .22 Winchester Rim Fire (.22 WRF). The WRF is slightly shorter, but actually shares the other dimensions of the .22 WMR and can be safely fired in .22 WMR chambers. WRF ammunition was largely unavailable for many years, but has recently been produced by a couple of manufacturers and is sporadically available.

Through the years there have been various other rimfire .22's, such as the .22 Extra Long, etc. However, the WMR and WRF are the only two "longer than long rifle" .22's currently available.

The old WRF may have been the best of both worlds. It featured a 45 grain bullet at a velocity that fell directly between the .22 LR and .22 WMR. Where legal, it made a heck of a turkey gun, and its solid lead bullet penetrated well, held together and damaged precious little edible meat.

In addition ot the AMT there was another auto pistol, the Grendel in 22mag. Awesome gun! It had a 20 round mag! The 22mag seems to loose quite a bit of velocity in a short barrel, however.
Peter.