I can't figure out why smaller shot is so ineffective at room size range, yet I've killed so many animals at 40 and 50 yards so easily. I know they weren't human sized animals, but we're talking much further distances as well. Sure smaller shot loses energy faster than larger shot, but that means it penetrates less drywall as well. It doesn't mean their opinion is any better than any of ours, but some like Sheriff Jim Wilson, and some Gunsite instructors recommend bird shot over buckshot for indoor use.