BradleyT - quick message, top of my head, and I may be wrong... If it 301s to the home page, and returns a 200, doesn't that "bad" URL that you want to kill actually continue to live on, taking on the content of your home page, and thus do you now not have 22 URLs all showing your home page as the content, i.e. 21 duplicate content versions of your home page? I believe 301ing to yoru hoem page is one of the wrost thigns you can do, unless I misunderstood your situation. We did this about a year ago, and got thousands and thousands of dupes of our home page, and lost our site links in the process, and our home page didn't come up for a site:domain.com search.