I performed a “field necropsy” on the bear. My first shot(a Nosler 150gr. tipped soft point) hit him just under the right eye, blew out the back of the skull, traveled along the spine, and I recovered the 30 gr. base of the bullet between the hide and the ribs on the right side. It had penetrated about 24”. I believe that was a kill shot but the adrenaline dump was so strong he just kept on coming. The fourth shot tumbled and made an elliptical entry wound at the left chest, traversed across the ribs, and created a 6” diameter exit wound that completely tore the right foreleg away from the shoulder. It was pretty dramatic. Best part is I lived to tell about it!
Most likely his forward momentum and some nerve reaction that he kept moving.
Being a hound hunter we head shoot a lot of bears out of the tree.
Good solid brain hits mostly result in DRT the way we like them.
But strange things do happen once the bullet leaves the barrel.