I have once. Now I don't know if it was the angle of the shot or what, but the arrow was going right for the middle of the back(facing away and below me). It should've hit him square it the spine between the shoulder blades, but it deflected off. May have been an ealry deploy of one blade? So I'll use them again but making sure I have a good perpendicular shot not allowing for the angle to be an issue.
