Most experts I have read, including those that have shot bears in self defense, recommend bear spray over a handgun. But, maybe it isnt practical for ya.
You may find this article from the Buffalo Bore guy interesting! Lots of good material there.
https://www.buffalobore.com/index.php?l=product_list&c=108
Buffalo Bore is good and proven, Underwood as well. I intentionally avoid Double Tap because they seem to mislead on their velocity, or used to.
Id use 200gr hardcast or make sure you test the 220gr well, lots of people with the G20 had the 220gr keyhole.
If you dont want to use hardcast maybe use 200gr flat nose FMJ or the Underwood XTreme Penetrator. I use Underwood 200gr Flat nose FMJ in my Glock 40 while hog hunting, but I would feel equall6 safe with Buffalo Bore.
If I were expressly concerned I would maybe get a good sling for my Mossberg and load 1 3/8 Brenneke Black Magic Magnum slugs in it, or buy a 500 S&W magnum with hardcast.
Just my 2 cents :)