If your asking this question, and your handle is "Popcanhunter," there is a 99.9% chance you won't ever hunt grizzlies... You would be best to look at a gun more suited to deer/blackbear... Any of the cartridges that work on one work on the other... Pick one from the following (partial) list... This will be a sliding scale (loosly) from (light with more speed) to (heavier with more energy/momentum); .25/06, .250/3000, .257, .260, 6.5X55, 7X57, 7mm-08, .280, .308, .30/06. And then you have the magnums or short magnums etc...Take your pick... Put the shot in the right place and they will all get the job done.