I have had entrance and exit wounds the same size and exit wounds larger before. So it really goes to each individual shot taken. If a bullet encounters bone it can not only expand larger but also blow debris out making the hole larger. Then on the other hand the skin of a deer is very strechy and will retract after a bullet exits. I had a buddy tell me he was having trouple with balistic tips not expanding when he shot several deer in the neck last year. Actually they did expand the hole just streched and close after the exit.