Alwion, unless you've seen an Atlanta Arsenal photo that I've never seen, I believe the photo of heavy-caliber Grapeshot held together by multiple vertical rods is from the Tredegar/Richmond-Arsenal site shortly after the surrender of Richmond. The photo is from the US National Archives. I only have a low-resolution version of that photo, which I will attach below this post's text. Multiple examples of that type of Grapeshot are seen at the mid-ground in the photo's center and right. Perhaps somebody here has a high-resolution version of the photo, and can "crop" that section of it, so its filesize won't be too large to post in this forum (greater than 256Kb, I think).
Apparently, that version of Grapeshot was strictly CS-made, and only in the very-late-war period. Being present in quantity at Tredegar/Richmond-Arsenal seems to prove it was not an imported version. I am not aware of any specimens ever having been dug. Apparently, none are still in existence, because there is no modern-made photograph of that type in any of the various books on civil war artillery projectiles, nor magazine articles.
Regards,
Pete