You'd think you'd notice a nail shot into your head. Then again, maybe not... My dad shot a nail through the webbing on his hand between his thumb and forefinger. I can assure you, he noticed!!! He also drilled a hole through his hand, not hitting anything major, thank goodness, and he noticed that one too! I think it was a bad power tool day! He's usually quite the builder. But, to his credit, he did build the entire barn with only 2 other guys and there was no power tool attacks on that one!