Doesn't matter if you're shooting 000 buck or #7 1/2 shot, it just blasts a big azz hole in stuff.
Buckshot is no more effective than anything else at ranges seen during defensive use.
Shotguns give a psychological edge to both the user AND the victim, but NO real advantage. Actually, there may be a tactical advantage to using a pistol rather than a shotgun simply because it can be handled easier in close quarters where even a short barrelled shotgun is a large weapon.
A Judge as her truck gun. Pistol loaded with .410 000 buck shotshells. My close quarter weapon of choice is my brand new Draco AK47 pistol. Same gun as a rifle but no buttstock and shortened barrel.
If any of you are seriously interested in a crash course in wound ballistics, FBI independent testing procedures for ammunition, the best CCW ammunition, bullet penetration, weight retention, and expansion....
Please read the link below. It was put together by some very smart people in the industry and the good folks at AR15.com.