There is no noticable difference in the killing power of a 308 Win and a 30-06 Springfield with deer type loads. The 30-06 is arguably better with heavier bullets but that is a topic for a different thread. This year I killed two deer ten minutes apart. Both were the same distance, relatively same size and weight, and both shot in the same location with the same rifle and same load. Both were broadside shots and both bullets entered right behind the shoulder and exited leaving a golfball sized hole. One deer dropped and one deer made it about 40 yards. Both deer had jelly for lungs. So how did one make it 40 yards? Who knows. Deer are tougher than most people give them credit for I guess. You are not going to drop them in their tracks every time no matter what you shoot nor where you "place the shot". Did my cartridge choice or bullet fail on that second deer? Not in the least. Would I prefer the deer drop in its tracks? You bet, but it just don't happen every time.