Don't shoot expandables myself, but I hunt with a buddy that uses them and I have seen 2 bears shot with mechanicals that I am very sure would have gotten away using a convential fixed head. The 1 shot in particular enteredto the right of the backbone and exited on the same side part way down the side. It tore such a big opening that the bear lost blood and entrails and was recovered within 100 yds. Just my observations with the expandables.

Jim