The weight isn't right and the metal looks wrong, too. But if you can get a good measurement of diameter that would be good as we could then match weight and diameter, the two most important factors in assessing these things.
Edit: looking again at all your photos (both posts) it looks as if there is a round plug. If so, that's definitely not a cannon ball. Solid shot did not have plugs and case and shells had fuse holes (which yours doesn't have).