I had a one shot stop using a Brenneke slug on a 4” diameter Christmas tree. (It was raining and I was too lazy to fire up the chainsaw).
There you go then.
I got charged by a black bear in my back yard in Wasilla, AK many years ago before I knew of Brenneke slugs. Shot him 4 times with a .308 semi-auto before all aggressive activity ceased. The first shot was in his brain and killed him - he just didn’t know it yet. When I worked in the North Slope oilfields I had personal experience with two one-shot kills on a Tundra Grizzly and a Polar Bear. I didn’t do the shooting but I was impressed with the results!