Also deer are not 3D targets... and you need to aim for the actual vitals.. not where they are on the side of a 3D target... IE if you hit the 10 ring on a quartering away shot... you're just about guaranteed to hit the shoulder blade!!!
I've never had an arrow "glance" off a deer... but I have had limbs & twigs send my arrow veering off course... many of which can be invisible until you get right up on them!!!