As far as I know, these were made at the Washington Navy Yard. I've got to check with a friend who told me the story once. They may have been made by apprentices. The Naval Gun Factory at the Washington Navy Yard was a major industrial facility and I'm sure had formal apprentice training programs. Making something like that would show skills in machining, patternmaking, mould setup, casting, etc. I should see the friend within a couple of weeks and will as again. Meanwhile I'll go look at one or two I think I still have around here. These may have been made in a few different sizes too.