Congrats on a fine looking buck.
I know the lousy feeling when you think you've made a bad shot. I had that happen last weekend. I was watching a doe about 40 yards away. I raised my rifle to take a closer look and decided she was too small. As I was lowering my rifle another bigger doe came trotting into my view from the right (my view was blocked to anything from the right by a big conifer tree). She was closely followed by a decent size buck. I quickly decided the buck was shootable and brought my rifle back up. I found him in the scope as they were moving right to left at a slow trot. He was in full rut mode. His head was down, scampering along like they do and close on the heels of the doe. I swung the rifle to lead him a bit and was surprised when the shot when off. Dang it! I thought I was too far in front and had cleanly missed.
To my surprise he dropped in his tracks and only the slight downhill and his momentum carried him about 10 feet. He lay there weakly kicking his hind legs and his head was away from me. I couldn't see any blood and had no idea where he was shot. I was sick with regret. The last thing I ever want to do is painfully wound an animal and I was afraid I had wounded him badly enough to put him down but not kill him. I also didn't want to approach him too quickly and cause him to panic any more than he already was. He was already terrified. I wanted to finish him quickly and humanely but I didn't know where I had shot him. Was it fatal? Was it just a crippling wound?
I said a quick prayer and decided to wait a few minutes. He died shortly thereafter. It ended up being the luckiest shot of my life. I must have led him just enough because he was shot just above the base of his neck and cleanly broke his neck. That's why he couldn't move and was only kicking weakly.
I'd still like to have that shot back because I know I didn't know for certain where that round was headed. I've never done that before on an animal. I've done that on targets plenty of times but never on live game. I don't want to be lucky with my shots on live game. I want to know where the round is going as much as is humanly possible.
OTOH, I've only ever lost one deer in my life. A few years ago I shot a doe. She was standing still, quartered and facing me about 50-60 yards away. I had plenty of time and made what I though was a perfect shot. She bolted and I gave her a few minutes before I followed up. It took me over an hour to find any blood and another couple of hours to find where she had laid down and bled a lot. I was able to track her for another 50 yards or so after that but then the blood trail just disappeared. I assume she clotted because I never found her or her trail again. To say I was distraught is a huge understatement. I don't particularly enjoy the killing part of hunting and I absolutely HATE wasting an animal.
As was said earlier, if you hunt enough this stuff happens. That doesn't mean we hunt irresponsibly but nature is the boss and all we can do is be as ethical, humane and responsible as possible. YMMV.