Why would you need a gun for a bear?
Were you threatening it?
Did it have cubs?
Was it eating or wanting your food?
Would you be, maybe, a little too fast to shoot a wild animal if you had the extra power, ready in your hand?
Would you kill it?
Where would you shoot this five hundred pound bear, if it threatened you?
Can you think of any alternatives to safely escape, without destroying something we're almost out of?