I've lost count of the number of whitetails I've killed with the 140 BT out of a 7mm rem mag, well over 100 I'm sure. Out of those I can't remember ever having an exit hole.
I don't believe that for one second.
I have probably shot close to a hundred deer and a few antelope with them out of a .280 going close to 3100 fps. I can only recall one bullet that did not exit.
That, I believe.