As has been stated. Physics does not support a theory that s baller can travel to fast for expansion. The opposite is true. If it is traveling to fast, you could get rapid expansion.

As for the exit wound, it is a mistaken beleive often that the wound is the same size as the entry wound. The bullet exiting stretches the hide as it exits. When the hide rebounds, it makes the hole smaller than it was when the hide was stretched.