I found the following written by JohnS in a different forum:
The Mark I designation indicates it was made for the Navy. In a tradition dating from the earliest days of smokeless powder for the big guns, the Navy felt it was necessary to have samples of the powder exposed to the same heat, humidity, and motion as the powder loaded in the cartridges. These would be checked periodically to make sure the powder was not deteriorating in potentially dangerous ways. Therefore they had powder sample tanks in many of the magazines on ships, especially larger ships like cruisers or battleships that still used bag type charges instead of brass cases. As far as I know, there is no collector interest whatever in these, and value is probably in the $20 or less range, if you can find anyone interested. There are also large powder tanks (about 10-25 gallon size) that were used to store powder in magazines at ammo loading facilities. There were copper and I think had wooden outer surfaces. A bunch of these are on the market now, also at low prices, and useful as scrap metal, or perhaps to polish up for the wife to plant flowers in. Unfortunately, not everything that is old, or military, has a lot of collector interest or value. John Spangler
Super Cool! Super Interesting! Very cool find!
Really good explanation by, John, also. Hope they don’t get scraped.
I agree with APFSDS- SCRAP???
I have a second job (part time) working with an auction company and all you have to do is mention that an auction item is form WW2 and the buyers go nuts!!!