I had the misfortune of having to shoot 4 bears last summer in the Arctic at close range in DLP situations. I used a 12 ga with 3" Winchester slugs in all but one situation. The other I used a 308 with 150 grain Remington Corelokts as I did NOT want a pass through no matter what.
I never found the slugs lacking, some were complete penetration and some were recovered. I carried a pump 12 ga in a shop-made rack on the visor of my work van every day. I happened to have the 308 handy when we were having problems with a bear visiting the hangar.
Several in town told me that they had tried everything and did not like the results they got with buckshot.
I suspect that the Dead Coyote 00 3" and 3 1/2" magnum loads would prove much better. They do pattern amazingly well.
