If you want wide shot dispersion so you can be fairly certain of a hit (leaving aside the idea of it being an effective hit, for now), why not just shoot a Judge?
I've seen strung shot, tailed shot, buck & ball, and a number of other things, some of them actually make a limited amount of sense, in a shotgun. They are more than a little foolish, and less effective, out of a handgun round.
I'm a longtime fan of the .410/.45 Colt combination barrel in a Contender, or other suitable handgun. The .410 shell is a very useful and potent small game shot, under certain conditions. Varmint/predator control being the most useful.
Any gun is useful for selfdefense, even the .410, and the right ammo allows it to be the most effective possible, but not every combination is as useful and effective as every other.
Shotguns, (and here we're looking at 20ga and up..) have a reputation for being very effective for self defense. But too many people only focus on the "multiple hits" aspect as what makes them so effective, and completely discount, or do not consciously take into account, the fact that what makes the shotgun so effective isn't the multiple hits, its is the mass of the projectiles that gets the job done.
Many discount the use of birdshot for defense, and, compared to larger projectiles, they have a point, small shot doesn't penetrate much, and is unlikely to be a good "stopper", from the point of view of being able to reach vital organs deep in the body.
Taking a standard pistol round, where the weight(mass) of the projectile is reduced by using multiple shot, and fastening them together, is only going to decrease the available penetration capability of the round in question.
Horrific surface wounds can stop a fight, and often do. But they cannot be counted on to physically stop an attack. From a self defense standpoint, anything that stops the attack, including anything that makes the attacker change their mind and break off is a success.
I'm not saying the "chain shot" won't work, a face full of birdshot has a pretty high "discourage" factor at across the room range, too. But, again, the birdshot is "bigger" mass when it hits than any common pistol round, too.
I do have to wonder about how trauma surgeons would view the use of "chain shot". OR the prosecutor....
All else being equal (and it almost never is) bigger bullets tend to work better.