I've killed a bunch of deer with buckshot. Hunting deer in front of dogs is my passion and the woods we hunt are thick. Most of my opportunities come at 75 yards or less and I've killed several at 60+ yards. I prefer the bigger 00 and 000 pellets. I started loading my own years ago to save money. Glad I did because finding a load your gun likes isn't always easy. These last few years, a lot of folks have been having to shoot whatever they can find and I guarantee you a lot of it doesn't pattern worth a crap. The importance of patterning your gun can not be overstated. When you find a load your gun likes buy all you can find. The load I've been hunting with for a while will put all 16 00s into 12" or so @ 40 yards and 20" or so @ 60. I feel very confident with it out to 60 or a bit more.
Hit a deer right with a load of buck shot and he will hit the ground so hard he'll bounce. Shoot one beyond the abilities of your setup and you will probably never find him if you kill him. A lot of times a deer shot with buckshot won't bleed much if at all. Not a big deal when you already have a pack of hounds on them. Could be a lost deer if you don't or don't at least have access to a good dog.
As much as I trust my shotgun, when I still hunt, I use my rifle with a nice scope on it. I know even if it's a close shot in the thick, I can thread a bullet where it needs to go. And if the deer doesn't fall there, he'll leave me a blood trail.
