Bone is like shooting a rock, breaks fragile bullets. Lungs contain more air then water or blood. To stop a bullet in a second jug with broken parts, I can tell you how far that will get you.
I disagree. I have never seen a bone that was as hard or dense as a good solid rock.
I am in your camp as far as penetration being a key for the best and uniform results, but if one can get exit wound i.e. two holes penetration with an EXPANDING bullet, so much the better!
I load medium-heavy HP bullets in my 44 Mag and 10mm, because they are known to be able to expand and still penetrate well on two legged targets AND large big game. With my 380, the first and last load up have been proven to penetrate 24 inches of ballistic Gel and about as many water filled jugs or cartons as you want to put in front of them. The 380 needs the penetration help from the hardcast, overweight flat point bullets and +P+ loadings, the 44 Magnum and 10mm do not.
