You can argue – and many do – that pepper spray is more effective bear repellent than any gun. We’ll leave that aside for now, as this blog isn’t called “The Spray Nut”. Instead, we’ll assume you’ve already debated pepper spray guns and gone for a gun. (Or you can decide to wear both.)
Unsurprisingly, I would tell you to take a shotgun rather than a handgun. Shotgun bullets have about three times the muzzle energy of a 0.44 magnum and make much larger holes. Unless you are an experienced handgun shooter, a .44 magnum is a difficult weapon to shoot straight, even at a very large target.
The gun should be a reliable 12 gauge pump with an 18½ to 20 inch barrel and should be a smooth bore with an improved cylinder choke.
The barrel should be simple with nothing more than a brass bead, if it is. Iron sights will not be needed up close and could catch something at the wrong time. I would tailor it with some sort of tactical slingshot that was comfortable to carry the gun through the brush for days on end until I finally needed it urgently. And, while the standard magazine full of four rounds should be enough, a magazine extension can help you feel better. Whichever weapon you choose, it should have a safety device located in the same place that your other shotguns have safeties (top, front of trigger guard, back of trigger guard) so that you can latch on. ‘remove without thinking.
For ammunition, a full barrel bullet like a Foster-style or a Brenneke is the best choice. The accuracy of the sabotage doesn’t matter, as you’ll only shoot a bear from a few paces away.