You bring up a good point concerning the cow's head. Cutting across and photographing a opened 'exit' would have shown if there was extra damage as in the extracted TSX hole, or merely a hole wiht minimal damage as in the full length Hydro hole. for further consideration?

Now - some things I find interesting - check the pictures of the hole where the X bullet was dug out compared to the hole where the Hydro was dug out. Now, cavitation would be directly related to the velocity possessed by the slug as it came in contact with the hide which is what stopped it(hide stretches out, stops the bullet, then slaps back against the body - this is normal). I notice the Hydro appeared to drift to a stop at the hide, creating no damage observable, a hole the size of or smaller than the slug - instead of a permanent cavity. I find that most interesting - of course, relatively high speed is necessary for cavitation, normally and a bullet impacting at 2,000fps or so, then slowing gradually to come to rest in the neck - granted a HUGE amount of total penetration. However, penetration while doing damage is the only penetration that makes a difference. Higher initial speeds would certainly help the Hydro live up to it's advertizing.

THAT is why I like to see exits - there will be a corresponding 'wound' all the way to the hide, rather than a mere pencil hole with no damage as the bullet 'coasts' to a stop against it? facts, thoery and opinion