Briley's short "Side-Kick" inserts are only for 12g
http://www.briley.com/side-kickchambertubesets.aspx
but they might make a short custom insert.
My experience, though limited, is that powder residue builds up creating a ring of hard crud in the barrel just past the end of the tube.
We'd be able to provide better advice with hard numbers. The pits just past the cones are of course a greater concern.

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