For deer hunting with buckshot, you really NEED to pattern YOUR shotgun with different buckshot to see what YOUR max range is with THAT shotgun.
IF you aren't willing to do that, you have NO BUSINESS shooting at animals with buckshot!
BUT, if you get a shotgun that patterns well with what ever buckshot you want to use, buckshot is VERY effective on deer sized animals. One of my uncles used nothing but buckshot on deer all of his life, and he killed over 100 deer with it, MANY over 50 yards away.
Over the years, he ALSO traded shotguns until he got one that patterened EXACTLY the way he wanted it to. And he kept that shotgun until he passed away many years later...
My dad (and us kids) also shot quite a few deer with buckshot, and dad also was very picky about what buckshot we shot through the shotgun we were hunting with.
Lastly, with buckshot, when you shoot at a deer far enough away that your pattern "starts to open up a bit", (you need to pattern YOUR shotgun to see what range this is for YOUR gun/load) ALWAYS aim half way between the head and the shoulder! This will put most of the shot in the head and rib cage for the quickest kills.
Like i said, if you aren't willing to take the time to pattern YOUR shotgun with the buckshot you want to use, then you shouldn't be out in the woods with it!!
DM