In rifles with much high pressures, I moved years ago to fire forming with a starting load for whatever cartridge it is. I would consider experimenting on just two of those cases. Maybe, anneal again, put a 410 starting powder charge in, probably have to hand seat a fiber, maybe have to trim it, probably a little less shot, and possibly qlue in as mentioned earlier an overshot card. Build a little safe back pressure, and it'll blow out. Pattern it just for grins?
Your brass may be pretty hard, just back of the point it didn't expand, or it may have acted like there was a bit of an air gap. Maybe it doesn't need annealing. I wouldn't worry about cleaning the annealing colors, until you have it humming along like you want it, and even then it might look neater, lol. Anyway, hang in there, it'll work.
