Why is it OK to head shoot a squirrel with a 22 but not a deer?
Just a little devil's advocate.

I'm obviously not going to take any bow head shots.
With a gun, I'm not going to say never as there are a few cases where I know taking a head shot would be done with just as much confidence as any other shot. HOWEVER, I really don't see me taking a head shot on a deer even if presented with a "best case scenario" that would allow it. I've seen a starving deer from a head shot gone arwy and don't see the need for me to put myself in a place to cause that situation.