I did the same thing at about 30yds last year on opening day of ML season, I hunt with a TC Hawken .50. I had a decent buck come up on my right and I was able to stand, turn and shoulder up because he was grazing along. I aimed center mass right behind the front leg and squeezed off...smoke everywhere and he just stood there looking at me for a second or two and then bolted, did not look hit at all, ran off like when they spot you and you move a little. I have missed before but it was under thread the needle type circumstances and that one bugged me all year long. I have been back to the spot multiple times and replayed the whole thing. The only thing I can figure is that I either shot low or the ball was deflected by a branch that I did not readily see (it was a tad thick in there, not extreme though). Sorry guys, I got typing happy, I know this is about 50 cal and Elk, not Whitetail just had to share the sorrow