Especially for not having practiced at near that distance. I have to wonder though, why haven't you practiced at that distance?
Note that unlike some others, I'm not questioning you for taking the shot. I wouldn't have done it, but then I don't hunt deer for meat. If I did (and my eyes were younger) the distance alone wouldn't stop me from taking the shot.
Sitting, braced, its not as difficult as many would believe. I can ring the 200yd rifle gong at my local range, standing, offhand, one handed with a 7.5" Ruger .45 Colt. But then, I've been shooting that gun with the same load (250@1100) over that same distance (from my back porch across the canyon) for 30 years. I know precisely what sight picture to use for that combination. And I have a really good idea of how to hold for all my other handguns as well.
You're walking about two feet off the ground right now, and you should be! Great job! The sad part is, that eventually it wears off. Enjoy the venison!
All else being equal (and it almost never is) bigger bullets tend to work better.