it would actually be a fair comparison to put the individual buckshot pellet up against a standard .32 bullet. It will not penetrate as well, nor will it impart any serious damage other than just penetration, but the general energy and wounding ability will be similar.
Buckshot creates very poor wounds. Once more, we have to look at history. Why were the pennsylvania rifles abandoned as we went to war, and we moved on to conical bullets? because round balls really stink as projectiles. 200 years of progress is being thrown out the window here, because of clever marketing.
Two placed rounds from any .380 handgun would cause more damage than 3 random pieces of buckshot in the velocity range of a judge.
In my mind, it always comes back to a few important points: first, a piece of buckshot isn't the same as a bullet, and it's a lot slower. Second, firing a load of buckshot isn't a controlled act, you know that by the time it crosses a room, they will have gone off of aim.
So, I choose to take control of my handgun, fire as many aimed rounds as necessary, and watch as those rounds either disable or fail to disable my opponent. I'm going to live, or I'm going to die, whatever. I am going to make the choice to either live or die by whether I can put holes in a guy's lungs, rather than putting my faith in a random pattering of seriously deficient projectiles.
But, I do confess, if I had the opportunity to shove something right in the perp's gut, would I choose a .410 buckshot load? heck yes, and as soon as I get the promise from God that I will never be placed in inconvenient circumstances, i'll throw away all of my hollow points and buy a judge.