Alex -
Again, nice job with those hackles. Question/suggestion in one, pertinent to Jim's question: Is it/it may be feasible to try RIT COLOR REMOVER. The question part of that is, though I needed to use it on clothes once or twice, I don't remember what the component is; presumably it's extra strength bleach. The suggestion is obvious.
Jim, are you from this area, Northeast? - Hunter's Angling Supply in New Boston, NH, sells Veniard Dyes, etc. Perhaps they have a color remover.
Alex, I've used H2O2 for most of it's suggested uses; will have to try bleaching feathers with it. Thanks.