Yeah, no beuno.
I heard others say it's more important to have a weapon you're very proficient shooting rather than big and mean as far as a caliber goes. So, the thought is…being very proficient with let's say a Glock 19 would trump a stubby 454 Casull that is unmanageable with recoil. I'm not opposed to this logic, but not fully supportive either. Yet, I'm interested with hitting a bear as many times as it takes till it's no longer moving. I can attest to being able to mag dump my 19 with precision and accuracy much faster than shooting six from my 5.5" .44 mag.
You're probably thinking…why would you use a 9mm when you could use a 10mm? Well, because I don't have a 10mm, unfortunately. It's on the list.
So, I carry my 19 loaded with Barnes 115 XPBs. They offer outstanding penetration, and I can shoot them very well. Plus, it's a Glock so I'm not worried about reliability. I don't carry an extra mag, because I don't think I'll get a chance at a tactical reload. If a bear is charging it's likely you stumbled across a bear at a close distance so things will happen pretty fast.
A side note: Two hunting seasons back I carried this 19 with a red dot. It snowed like crazy while I was out hunting. There was no keeping snow out of my red dot and it resulted in an unusable pistol as the snow caked up in the window and then stayed foggy where there was no sight picture. So…lesson learned, Irons only for a bear pistol. One, for the weather scenario listed above. Two, you don't want your batts to die when a big bear comes charging at you.
To be clear, I'm not saying 9mm is THE bear round. It's just what I have that I'm comfortable shooting with confidence.