In interior (not mixed interior/exterior) home defense situations, buckshot and slugs are totally out of the question, unless perhaps you are using them in a .410 shotgun.
In a shooting we had at my Sheriff’s Office several years ago, the offender, a man of average stature, was shot in the area of the navel square on with a Remington® 870 12 gauge pump loaded with Remington Reduced Recoil 8-pellet (yes, eight pellets – it eliminates the one stray pellet normally encountered in 00 buck shot patterns) 00 Buckshot load at a distance of about seven yards.
This load, by the way is excellent, one of the very best law enforcement loads, and one of the tightest patterning loads I have ever shot in any shotgun. It increases the safe usage of 12 gauge buckshot well out to 30 yards, and is great for headshots at seven to 10 yards, or a little further out in improved cylinder choke barrels.
Anyway all eight pellets blew through the suspect’s intestines and impacted in the dirt on the other side of him. He stopped his threatening actions but did not die. This means that if you hit an offender square on (facing you) with 00 buckshot, even with a lower velocity reduced recoil load, the pellets can and do punch right out the back, endangering others.
Remember, the load is called “buckshot” because it was originally used for killing large animals, like buck deer, and in places like India sometimes tiger. It is powerful stuff. Legendary in terms of its killing and stopping power, buckshot is the shotgun round that people fear the most.
Most criminals are too dense to realize that they face an equal amount of damage, maybe even more, due to shredding effect of all those little pellets from a close range load of AA Trap and Skeet as they do from the 00. However, don’t be misled. These loads can and will punch right through drywall at close range. Remember, they only spread one inch per yard, and at close range it is a lot like getting hit with a single, solid projectile.
If you have overpenetration concerns, you may want to closely examine whether a shotgun is the best weapon to choose. A lower powered handgun, which can still punch through a wall, but is only putting a single projectile at a time through it (assuming you are missing your intended target), may work out better for you, especially in an apartment where there are neighbors close at hand. Even then, you should limit your handgun ammo selection to pre-fragmented rounds like the Glaser Safety Slug or Magsafe.
For general home and property defense, where over-penetration is not a major concern, buckshot of various types and sizes is probably the best choice, not only for two-legged predators, but for large four-legged predators at close range as well. Those trap and skeet loads run out of steam pretty fast in terms of effectiveness over distance.
The law enforcement community dumped the use of #4 buckshot as a duty load and went back to 00 buck when we began finding out that #4 wasn’t giving the desired penetration. Rifled slugs are mostly to be avoided unless you need the longer range and penetration a rifled slug affords, or if you live soemwhere like Alaska, where your four legged predator problem involves large animals like bear, rather than the coyote of the Midwest.
Yep, for Alaskan defense, 3- to 3-1/2-inch magnum rifled slugs, and a six to nine round magazine capacity sounds like an ideal combination.