Hi Dave - Taylor built a .58 smoothbore pistol for a friend and shot it.
That day, I was shooting my .54 barrel (66" twist) with 00 buckshot and a patched ball.
I put a patch over the 3 buckshot on top of the ball.
At 12 yards, all the .526" balls were in the 10 ring of a B27 target, yet the buckshot always radiated
around the central ball, about 5" from it, in a circle, hitting the 8 & 9 rings.
That would make an effective self-defense load.
This is the smooth bored pistol Taylor made. It was subsequently lost in a house fire.