I've never had an intruder inside my house, but a few months back when I first moved into my town home condo, that has a layout (ironically) like a fortress, my wife's car was being broken into. Well I keep a Mossberg 500 underneath the bed with 4 in the tube at all times, (3) bird shot, (1) 00Buckshot. More Birdshot than Buck mainly because I don't want to mess up the real estate should it be needed indoors, and birdshot at the ranges you'd be talking about in the house is enough to blow a man clean in half anyhow, and messy to begin with.
Anyhow, I went to the second story, opened the window and merely racked a shell into the chamber. Man I tell you I've never seen 3 pukes run so fast in my life. If it were indoors I'd just rack it and send them to whatever GOD they believe in though as they have no business in my domicile. *Thus I guess it works sometimes.