I use the HR all the time, and I do not use sharpshooter at all...
I've been able to get a decent number of headshots without it when sniping... I find that (in my experience) once you get use to how the gun sways, the effect becomes less noticable (since SS reduces this)... mind you, it took a while to get used to this.
The SAR's can still be a hassle with the stun of repetitive shots.
I tried out the HR last night for the first time in a long time. And my only problem is when I don't get head shots. You know when you're laying wait and some guy oops his head up from behind a wall looking for someone and he's completely unaware of you. I line his head up. Pull the trigger... Boom body shot! **bleep**!? The red dot was CLEARLY in his non-moving head.Basically the only thing above cover I can shoot was his head. Now he knows where I am. Ducks and heals. And I'm reloading. So frustrating.
Is there a magical spot I should be aiming for?
I've never had this happen to me. Maybe your shot really is just off?