Not sure how it happened but recently (after about 70 hours of gametime) VATS is now giving me a 95% hit chance when aiming for the head at all times. I stood at the top of an appartment building with a shotgun aiming at people in the street and while every other location had around 7% chance to hit the head was still 95.

Wish I could be more helpful as to what triggered it but don't remember if I had taken any new perks just before this and I can't remeber what I was doing at the time. All I remember is that it was around the time or just after I entered vault 114, and don't quote me on that because this game just destroys my sense of time. Like I said, not helpful.

It's not a big deal when I'm using my sniper rifle as I have this thing upgraded to the max, have 10 perception (pluss glasses bonus) and the sniper perk, headshots are common anyway. But when you can headshot a guy with a silenced pistol from another building (and considoring with a full AP bar I can squeeze of 13 rounds right now) as I have gunslinger, Mister Sandman and Ninja... it gets OP.