I don't know why people are so hung up on an exit hole. The lungs on a deer are about 25% of the broadside view, and if you shoot them in that area with any modern centerfire cartridge, they are going to be laying close enough that you won't need a blood hound to find them. If you are hitting them bad and expecting a bullet to bail you out, then you are the problem, not the deer. I've killed more than one thousand whitetail deer in my life, and I've made about every mistake you can make in that pursuit in the last 30+ years, but if you go get your xx caliber rifle, and you go buy the worst garbage ammo Walmart sells, and you hit them in the lungs with even anemic velocity and they will die quickly. Bullets aren't magic, you have to put them where they belong.