Hart, One thought I have that makes sense to me (and maybe not to anyone else and that's OK) is birdshot for an in house shotty. Close range, birdshot is lethal. AND less chance of any over penetration that you MIGHT have with 00 or slugs. Just me and no evidence to back it up. I've only had smaller houses where the MAX range would be (inside the house) 10-15 yards TOPS! I just think I would personally prefer the birdshot. Now to me birdshot is about 7-7 1/2 shot)