[cannonmn]

re: post no. 12 above. Those shells are 15-inch. The photo is a fairly famous one from the "Miller Series" etc., and Battery Rogers is only a few miles from where I live, am quite sure it had 15-inch guns. Another way to verify this is to look at how tiny the fuze hole looks; at the time the US had somewhat standardized fuzes.

Michael knowing your expertise in many topics I will accept for now the notion that all of the projectiles you identify as such, are in fact such, but must express some wonderment that those with considerable jagged projections, not the result of age or damage, had been accepted into service in any country. Perhaps some could be foundry rejects discovered at the site of an old furnace?

In the US from at least the early 19th C, there was an exhaustive process of casting then hammering then gageing (sp?) cannon shot to ensure their surface regularity and integrity and acceptable diameter. One gauge was actually a tube the ball had to roll down, and would not pass if oversized. Another test for each had the ball dropped from something like 20 feet onto an iron anvil to ensure it would not break easily.

I am a bit hard-pressed to believe that the US was the only country that had such high standards for shot. Many of the balls identified above as shot, I doubt would have passed in the US even as grapeshot balls.