Yes, I've taken head shots...With a .22 rimfire as a kid while squirrel hunting...I guess I've killed a dozen that way, all dropped at the shot, no different than killing hogs with my dad's .22 pistol...
I have killed one with a head shot with my .243, it was one morning, during doe season...I was up in a white oak overlooking a cornfield...I could see the deer's head while it was pulling corn off the stalks, range was about 100 yards...The bullet hit in the back of the head and that was that...
I take lower neck shots when a deer is quartering to me, the bullet enters the base of the neck and exits the opposite shoulder...The other time I take them is when they are looking dead at me...I hold just below the white neck patch...Both shots drop them, no tracking needed...