I dislike the use of buckshot for big game in the hunting context and I don't think shot of any size should be used for big game. True there are jurisdictions that require the use of buckshot, but that just goes to prove that elected officials and bureaucrats don't understand the subject. If by ball we are referring to a spherical ball, my objection extends to its use as well, be it propelled by a shotgun or a black powder rifle. If the ball is made heavy enough for the job, it must be elongated to to take the shape of a minnie ball in the black powder rifle or a slug in a shotgun. Spherical projectiles are ballistically challenged in that they are light for caliber and have neither a longitudinal axis to rotate around nor a nose heavy configuration to ensure a modicum of accuracy or straight line penetration. Spare me the stories of the pioneers, I'm sure they would have traded their round ball loaded muskets for one of our slug loaded 12 gauge breech loading guns in a second.
Even the LEO community has come to realize that a buckshot loaded shotgun is less effective than a pipsqueak round like the .223. Anyone who doubts this should consider the findings from the infamous Miami Shootout between two armed felons and the FBI, it's interesting reading for anyone interested in terminal ballistics. But I digress, the context is shooting bears, and bears are bigger, denser, and have thicker hides than people . . . well most people. The 12 gauge' s versatility comes from the fact that when loaded with slugs it can fill the role of the powerful rifle, thus elevating it from it's place as a small game and bird gun. I don't understand why, except under specific circumstances, anyone would choose ammunition that makes their gun less effective when hunting big game.
Now, if buck or ball suck as killers of big game by themselves, loaded together in the same cartridge as buck and ball they are even worse. The ball has reduced velocity due to the weight of the shot in cartridge which further reduces it's already questionable penetration, and the shot is less effective than it might be because due to the presence of the ball there is an insufficient mass to inflict the tissue damage necessary for a humane kill.
, that situation involved body armour....
...slugs would have left welts 
, indeed 
, but as to the idea of penetration...
All legal.
