kilibru:
As I see it, you have three choices:(1) live with the rattle (2) send your barrels back to the "well known refinisher" and demand they do the job right (good luck) or (3) send the barrels to a true professional and have the ribs opened, joint flushed and cleaned, and ribs relaid. Sadly, experience is often a heartless and expensive teacher.

There is a certain "well-known refinisher" in that part of the world who is famous for the problems you describe.

Best, Kensal