Ackleyman,
I don't know for sure either since I've never been able to recover one. But you're right. Exactly right, those cats run like mad when hit. That's what makes me think the bullets are not expanding. I'd think that, even if they were blowing up on the surface, they would at least fall then get back up from the shock, and there would be a good amount of blood at or near the spot of impact. But they jump and run or just start running. No blood trail, or very little, in my experience with them. The only one I remember being DRT was a head-on shot, where the bullet would have had to penetrate the entire length of the cat.
I just know that we're on the same page... the Supreme's sure leave a lot to be desired as far as terminal performance on cats and larger.