Im from the school of thought that bullet placement is one of the highest factors on the list. many prong horn hunters out west say a 70 gr. boattail is the best thing to use on prong horns, I dont see a big size difference bettween a prong and an average whitetail. Ive talked to a few old-timers who often took whitetails with 22 long rifle. like I said, shot placement! I think 75 gr. is just fine for deer. But thats me. I understand some of them varmit bullets are designed to blow up/ shatter on impact. Id just make sure the 75 gr. bullet is designed to mushroom. Thats just my worthless opinion, but Id really like to here some other ideas!