IN .44 Magnum (asking those who have experience) how close you have to get to the grizzley to be effective?
The .480 Ruger is a great modern cartridge for your target. With the 500 mag you wouldn't have to chase it down, which is great because you will be tired from lugging that huge impractical revolver around.
The .357 would be inhumane at the least and probably dangerous. The larger diameter bullet always gets the nod in hunting, put at least a 4 in front of it. Nickels.