I live in the Rockies west of Denver. When I travel to the city there are human threats. When at home, sometimes working in the yard there are animal threats. So far in Colorado I have had no direct human threats, but have had many bear encounters including break-in.
I carry a 40 cal because it is concealable, I can have rounds suitable for defense against humans like 180 gr JHP Gold Dots and I can also have the smallest round chambered for the Double Tap Wide Hard Cast Flat Nose bullet, in the 40 cal I use the 200 Gr at 1000 fps from a short barrel. This round is probably a 3 ft of bear penetration. 9mm has no comparable dangerous game loads or I would probably carry that.
Phil Shoemaker killed a charging brown bear with Buffalo Bore 9mm 147 gr. +P hard cast. I'm not advocating for or against but it's there and obviously can work in a pinch.
