This is a yes and no. I am working on something like this at the moment for a client, where they want different bullet damage to different parts of the body in TF2. As far as TF2 goes, theres only two hitboxes, head/torso, and the sniper rifle is the only weapon that can make use of the head hitbox.
I am looking into using the mins and maxs of the player models though to find a more accurate idea of where the projectile impacts the player. If I figure anything out I will let you know.