i was using a 150gr bt in my 270. i've shot about 15 - 20 deer and everyone of them did NOT have a exit hole. it didn't matter if i shot them on the shoulder or behind the shoulder the bt "shredded itself like a hand grenade!!! 150lbs avg is about right for my area. i never had a deer that runs off, it will run about 30-50 yards and die.
the big reason i cast is blood trails. the boolit goes in and comes out and the blood pours out.