The two photos below show what remains of full boxes of cartridges that were submerged in the ocean for over 100 years. Oddly, portions of some of the boxes remain, as can be seen in the lower photo. These were boxes of 50 cartridges each, of an unknown caliber - possibly 44, and could be rimfire or centerfire. I have not seen a photo that shows clearly whether or not the cartridges have an external primer. As can be seen in the top photo, they have a round nosed lead bullet. I suspect the grooves that show on some of the bullets are the result of the bullets having been forced slightly out of the cases as the result of swelling of the powder charge.
This photo below shows the UMC ‘warranted’ statement on the sides of two of the boxes with the Union Metallic Cartridge Co signature. What firearm they were ‘made expressly for use in’ is illegible, but I can make out ‘Model New Army Revolver’. I believe Colt and Remington both produced what they called a New Model Army Revolver; I’m not sure if any other maker referred to their early revolver as a New Army. The specific wording on these boxes could possibly be used to determine what cartridge they are. Anyone have any ideas?