I guess that you could say that the Black Diamond is free floated since the stock is not attached to the barrel anywhere.
I had the same "problem" with my Black Diamond. If I recall correctly there are only two screws that hold the stock to the frame. These are on either side of the trigger guard aren't they? This leaves the entire forend unsupported and it made the forend rattle against the barrel, especially if I carried it with a sling over my shoulder. I solved the problem by putting some moleskin around the barrel channel between the end of the stock and the barrel. This seemed to help the rattling.
Hope this helps....
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