I have a couple of cases of No 4 buck for emergencies, and they really pattern well in the Model 12 Heavy Duck. Nothing larger recommended.
The No 4 buck is also the FBI choice in their shotguns. I have an early Model 12 riot gun from my Federal Law enforcement days and it is cyl bore-
handling all buck shot sizes. Own 5 Model 12 Winchesters, so the chance of accepting a lesser grade of pump shotgun is null and void.
Of course, nothing will outshoot my SuperFox if it flies or gobbles beyond 50 yards.

"The credit belongs to the man who is actually in the arena-not the critic"-T. Roosevelt
There are no atheists in fox holes or in the open doors of a para's aircraft.....