I've never tried Buckshot on Hogs, my instinct says no. I have used slugs and they work well. Hogs are different than Deer and other larger game, they have a higher resistance to shock and their hide is self-healing. IMO unless you got lucky it is doubtful you'd bring down a Hog with any sort of Buck at likely distances.
The common local wisdom says the bigger the better for Hogs. You never can tell when a Five+-year-old Boar is going to wander by and you don't want to be under-gunned. Also the bigger the hole in and out the better if you have to track one. They have self-healing hide and a wound can pucker shut and stop the bleeding pretty quickly. You have to figure they are basically tanks that can barrel through thickets at speed, their hide has to be tough.