Mark,
I've seen what many would call "splash-back" with a 140-grain TSX from a .270 on a coyote. Entrance hole (right behind shoulder) was 2-3" across. But the bullet did exit!
In my experience splash-back depends almost as much on what the bullet hits as the bullet. In this instance it hit soft tissue initially, but hit a rib after that. Maybe a piece of rib "splashed back"....