Not many have ever HAD to it, Thank God!
Lead on an animal that is trying to make you lunch = ZERO!
More likely , one would be hard pressed to get the gun out of the leather in time to get it into his mouth before he chomps down.
Attacks happen so fast, the better use of the pistol is to put oneself out of his misery after the critter has left the scene.
Apparently you're mistaken, as it seems several successful defenses against griz with firearms (including handguns) have been documented.
