>>415394Collapsible and take-down rifles are fun if you want to kill squirrels or other small game, but they are ill-advised for wilderness defense (in my opinion) because they are slow to deploy, and get in the way of your other activities (see picture). If I'm out there to hike, then I want my hands and feet free for all 20 miles that I hike each day. I don't want ANYTHING swinging back and forth on my backpack. Ditto if I'm fishing, snowshoeing, doing photography...
In my experience, bears can either give you time to prepare for them, or they can run up and surprise you, but when they are checking you out, giving you time, the thing is that it's not in your best interest to waste your time and attention fumbling with a rifle strapped to the back of your pack. You need to be able to deploy a firearm quickly and fluidly.
That leaves pistols and revolvers. I would carry anything from .357 magnum and up, although a lot of people will carry the biggest guns that they can shoot (.44 magnum, .454 Casull, .460 S&W magnum, .500 S&W magnum). The problem with the big revolvers is what if one of your arms is compromised? (say the attacking wild animal has its teeth sunken into your forearm). I used to own a Ruger Super Redhawk in .454 Casull, and it was not something I could safely shoot one-handed. If your gun is too powerful to be shot one-handed, then it is not appropriate, IMO, for wilderness defense.
What I currently carry is a Glock 20, which is on my backpack's hipbelt. I also have a small .380 (backup gun) in either my front pants pocket or my backpack's hipbelt pocket, which varies from either a Ruger LCP to a Sig P238. The 16 rounds of 10mm is my main defense, but in case I limpwrist the lightweight polymer gun (easy to do) and cause a jam, the little .380 is better than nothing, in a pinch, at close range. Ideally, I'd actually want an lightweight revolver as my backup gun, but the reality is that the .380 micro-compacts are lighter and easier to keep handy.