Buckshot loads are very specific, you can't just substitute buck for shot. It has to be loaded BY THE NUMBERS. By that I mean they're counted, and loaded in layers, or nested, only a specific number can go in certain gauges.For instance, 00 buck can only be loaded 9 to a 2-¾ inch shell.
Normal buckshot is swaged nearly pure lead. As such they deform greatly under acceleration. That's why buffer is needed if you want any kind of tight pattern. Ballistic products sells nickel plated buckshot, it's plating makes it stay round, then with buffer besides, you have real tight patterns.
http://www.ballisticproducts.com/
The Lyman shotshell handbook has many recipes for buckshot. They tell you powder charges, wads used, hull types, and whether to fold or roll crimp the shell.
Unless you live in the middle of nowhere, I wouldn't suggest buck or slug for home defense. Both will penetrate walls, once in another room, or outside, you can't see who else might get hit.