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Bear spray never works if mama has cubs.
Casul .454 is an alternate spray that rarely fails.
velocity = approx mach 2.
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Actually, there are legions of people who have been badly mauled after using a handgun on a bear. Even some of the vaunted magnums.
You are going for a target 1/5 the size of a human brain, encased in a dense bone skull. It is in a full snarling charge, covered in fur. Your adrenaline WILL be pumping. A miss is worthless. A wound other than to brain him is worthless and will enrage him. Mere mortals should have bear spray, backed up by the handgun for a final attempt to save yourself.