I don't believe that the poster is talking about a .22 Magnum, I believe he is talking about the old .22 Winchester rimfire. Now obsolete, it is not interchangeable......a .22 short or long may be a loose fit, but will usually not fire and if it does the cases will split. Someone recently made a run of this ammo but I don't remember who. If the poster is not talking about the .22WRF, he should be more aware of the gun/ammo he is about to use as this is a safety issue.