Used to be an old guy by the name of Elmer Keith that wrote for Guns & Ammo magazine for a few years.
He had a lot of experience killing large dangerous bears up north.
He carried a double rifle like those used in Africa for elephants, water buffalo, etc.
When asked why he carried such a rifle for brown bears he replied, "The bullets go all the way through, and I want them to bleed from two holes at the same time."
Anything that big, that mean, you want to die quick.
I'd still want to be up in a good stout tree before pulling the trigger. And have a big bore handgun in a holster on my hip.