In the early days; in my Greener's book he states that
gun with a rifled choke section of the barrel, called
12ga paradox shotgun/rifles, with slugs, heavier powder
charges than shot loads, could hold what amounted to
about 5 inch pattern at 100 yds.
And still had 1800 ft lbs energy at 100yds.
And that is with guns with lighter, weaker barrels
than we have today, so our work is a good extension
of what the early big bore guys did.
And then the 4bore for guys liking a big challenge, 3rd picture...Ed