Go to 33:41 in this video. Heimo Korth and his wife live in the Arctic National Wildlife Refuge.
Kills a grizzly with a shotgun this part of the video.
https://www.youtube.com/watch?v=Iq0rZn8HFmQ
To be clearer, a grizzly can be killed with a gun but not always right away. They can charge after they are shot. There seem to be many accounts of this so it’s safe not to assume the animal is dead or incapable of attacking after shooting it.
Those fellows in the video took a chance the bear was dead. It was, they were lucky. It wasn’t necessary to doo what they did. Hunters say to wait 30 minutes in dead silence before approaching a shot grizzly. I think that’s a good warning.