Why did you think you had to hold under? Point of aim right behind the shoulder socket is the sweet spot unless your looking to anchor the bear by taking a shoulder shot.
From an article I read on angled shooting ("Angle Shooting" Correcting for the effects of gravity By Ward W. Brien) which stated that when shooting at an angle (regardless of whether it is an incline or a decline), the effects of gravity are reduced. Thus causing a flatter trajectory that impacts higher than a flat plane shot. The article refers to long range shooting, but I figured the same principles apply.