I took my wife's grandfather's Crescent 16 guage double out one day, deer hunting. I had found some #1 buck, and told my wife I would use the gun at least once just to say that I deer hunted with it. I shot a young doe at 25 yards. She sagged at the first shot, but did not run, so I shot her again. She ran onto my neighbor's property and died in front of his hunting cabin. He had about ten hunters in there, playing cards, drinking coffee, and waiting for lunch. The rack on the porch was lined with wonderguns. I went in to tell him I had a deer and they all piled out to have a look at the deer and then at the old Crescent. It tickled me to think that one old shotgun in the field outperformed ten wonderguns in a rack.
The doe was hit by two pellets, the first I suspect was in the liver, because of the sagging. The second was in the lungs. The doe still ran nearly 150 yards across open ground. Being mainly a rifleman, I was not too impressed by the results. If I use buckshot, it is in situations where 25 yards would be a long shot.
Some years ago, I ran a series of tests using a selection of 12 guage buckshot, and my collection of 12 guage shotguns. ranging from a single barrel H&R to an Antonio Zoli o/u. I was not able to find any load and choke combination that would place more than three pellets in the vital zone at 25 yards. I cannot imagine trying to take a shot with buck at over 25 yards.