The only 22 ammo that is safe to fire in the 22 magnum chamber besides 22WMR is the almost obsolete 22 WRF, aka 22 Special. It is the same diameter but the case is slightly shorter than the 22WMR. Standard 22 rimfire ammo will fire in the magnum chamber, but as has been noted, cases will split every time. Not safe at all!! Regards, Eagleye