Not to spoil fun with accuracy... I served as a grant writer in support of the USS Constellation Museum and can tell definitively that the 1854 sloop-of-war USS Constellation, which now resides in Baltimore's Inner Harbor, was still a commissioned ship until 1933 and, though entered into decommissioned status after then, was used as a flagship by Vice Admiral Ingersoll through 1944. Until then, she had 25 working guns ranging from 200 mm chambered shell to 32-pounder long gun and was actively used through WWI as a practice vessel to train US Naval Academy recruits. Though sorely out-of-date, they trained the cadets with these guns (a rigor or right-of-passage of the academy I suppose) and used live artillery in practice. I'm not sure of the rest of the fleet's artillery around WWII, but I remember discussions of other such sail ships used in training, so I imagine the cannon balls are leftovers from those vessels or collected from Navy-controlled land-based artillery installations that had been decommissioned but never disarmed. If I remember correctly, there were at least a dozen such installations along the MD, DE and VA coastlines and many more along the eastern seaboard to warrant stockpiling at Norfolk.
