Here is a rather eye-opening test, pitting Fiocchi 9 pellet 00B against a rifled choke tube and a cylnder tube at 5, 7, 10 and 20 yards.
It seems buckshot, at least when contained in a plastic one piece wad, delivers quite usable patterns at defensive ranges.
I suspect the relatively loose fit* of the pellets in the shotcup, may have contributed to the pellets exiting without much spin as the wad was slowed by rifling contact at the muzzle.
Indeed, i was suprised at the resulting patterns.!
What say you?
* A customer review on Midway USA website indicated the pellets measured around .295", definitely on the small side.