The only immediate kill shot on the deers head is it's brain, about the size of a small fist. If you can consistantly hit that free hand @ 50yds, you are a very good shot, it doesn't take much of a piece of brush, fast breathing, a jerk on the trigger, a slight bump of the sights to pull a bad shot! But consider a miss of 1/2" gets you nothing but a very badly mangled deer head, which will surely die a much longer slower death than a gut shot deer
At 50yds I'll take a "spray & pray"

shot in the boiler ahead of a standing head shot EVERYTIME, & I'll also have a much higher kill percentage
I'm not 100% against a head shot, at maybe 50ft on a standing deer maybe? if circumstances were right..I donno I guess I've never been in the right circumstances