I have been experiencing on both Xbox 360 and One where head shots do not obtain a kill.
I cant count how many times I would get feedback of the hit where the player shot had only their head in view yet there is no kill. Not just a single shot, some times its several to uncountable hits.
I went from being in the top 7% in head shots last month to barely managing to make the required ten shots just to get a perk.
Is anyone else experiencing this?