My wife has some advice on using firearms for bear defense.
It was around the time of the 9/11 attack, and her dad had just passed, so she moved back home with her mom. Home was in the mountains west of Pueblo, Colorado.
Her dog had gotten into trouble, so she put her in a dog crate outside. She hadn't had enough time to put the kennel up yet, so that had to get the dog by for the night. As she left, she told the dog, "And I hope the bears get you!".
About midnight, she saw the motion light come on. Yep, a bear had come in after chokecherries and garbage. Now worried about her dog, she asked her mom, "Where's dad's guns?".
She grabbed the first one she saw, and headed out the door to protect her dog.
At some point, she decided to shoot the gun into the air to scare the bear away. She pointed the rifle up, and pulled the trigger. "Pfft".
It was a .22 rifle, loaded with CB shorts.
She doesn't recommend this particular cartridge, BTW.
Then there's her cousin, who went out to scare the bears out of the apple trees by banging a couple of steel cook-pots together. She got their attention, too. All eyes were upon the dancing show while they continued to feast on apples.
This isn't recommended either, btw.
I just wish more people took bear defense as seriously as these two do.