Big Bull:

I saw tests in the past that use this:
1. Paper target
2. 1/2 inch thick piece of 4# closed cell foam
3. Piece of paper
4. 1/4 inch thick piece of plywood
5. Piece of paper
6. 1/2 inch thick 9# foam
7. Piece of paper
8. 1/2 thick 4# foam
9. Piece of paper
10 1/2 inches thick 4# foam

Machining the rotation 20 inches thick.
The hard partis holding it together.
After the shot you can get each piece of paper and measure the cut?

This is just what I saw.

It is very hard to replicate an animal tissue and bone and mussel mass.
Animals like us have allot of water mass.

Hope this can help.