"Sounds interesting if you can make it work. Would a 10 gauge work better?"
More volume for the can (barrel substituting for a can) would naturally be better, but host guns would be very rare. I can't think of the last time I saw a single shot break-open 10 gauge for sale. 12 gauge platforms are as common as dirt. I've looked at the internal volume available, bearing in mind that the length of the can is fairly long, and it's definately adequate. Compared to most of the .45 ACP cans it's positively overkill. The trick will be to space the baffles so that they are positioned correctly while not eating up internal volume. Still playing with that part of the plan.
To the second poster: Yes, I am very aware of BBL inserts of all sorts. While I appreciate your thoughts, they stray very far away from the design idea that I want to persue. It's just one tax stamp cost risked to see how it works. Nothing ventured, nothing gained. I will look at the extractor that you mention.
Any positive ideas on baffle design would be appreciated.