At inside the house ranges, there's not going to be a lot of difference between getting hit by buckshot or heavy birdshot.
All it takes is that one time you happen to be the unfortunate one that gets attacked by the severely determined attacker that is hopped up on pcp and can't feel that superficial damage.
There no other sound like that of a 870 shotgun being chambered.
Right I keep the shot gun in patrol ready. I just put the plug in it last night because it's bird season. I plan on getting her the 20 and loading it 000 or 00 buck. Bird shot gets people killed and not the bad guy like everyone says it underpenitrates it sucks for anything other than birds! If she can get to the shotty great but if the 9mm is closer I havs no problem with 17 rounds of 9mm HP's going into the bad rather her kicking and screaming. So that is the plan right now it's my 870 when she gets her 20 that will be the go to long gun.
For use inside a home 00 buck (or #4 buck) will penetrate more than just the target. Use whatever you feel most comfortable with, but I would be very careful of the background - especially when using buckshot in a family home.
Anything that is going to be able to reliably stop a bad guy will do that, though. A lot of the "good stuff" is at the back of the human body - the spine, the descending aorta, which runs right next to the spine... You also have to figure that if a bad guy is armed, he may have his arms up in front of his chest (go point an unloaded gun at a mirror and note the target it presents), so you might have to shoot through a good distance of arm.
You should always pay attention to rule #4, no matter what you're shooting.