BYU conducted a recent and poorly conducted study of firearms used in bear attacks.  Just having a gun isn’t enough.  A.  You have to have a gun and ammunition capable of stopping a bear.  B. You have to know how to use it.  That requires training.
The news report in the Trib makes mention that people don’t practice in a realistic manner… That part is very true.  Just punching paper isn’t training. 
The key in a sudden bear attack scenario is an accurate first round hit made fast.  Very fast.  You have one shot and no time to take it.  Thus is the 21 foot rule to the extreme. 
Practice with your bear gun from slung on the shoulder, snapping the gun off and breaking that shot accurately.  The time to strive for is about 1.5 seconds.
Good luck with that.