Good that you test. However, I would have tried to simulate flesh and bone. I have always thought that you could use a plastic bin filled with wet news paper, with wood of varieing hardness placed in it as a good test. THe wood would be placed 6 inches in then more paper then more wood. This would simulate skin, flesh, shoulder, organs, shoulder, flesh, skin. You could play around to get the right combo of wood and paper.

Colorado