I believe the OP mentioned either a 48 or an 18 in addition to his comments on the .22 magnum cartridge.
I assumed the OP knew about the chambering difference when he mentioned the Model 18 as a possibility over the Model 48.
I do know the differences. I've just had to revoke my membership to the "Gun-of-the Month Club" so I can really only save for one or the other at this point. I'm just trying to figure out if I want to jump into a .22 magnum or not.