here is something someone might be able to use. a dude i met while living in fla several yrs ago told me this tale i think was fact as his father confirmed it. the father was in the service and on weekends the two of them would go out in boat and pick up dummy bombs that had been dropped from planes during target practice for re-use. one day while floating in water the dads foot hit something and he stood up on it. he went down and discovered it was a cannon standing on end. further inspection revealed 11 of these cannon still standing on end. . the father took knife and scraped a little metal off of one and had it tested. he was told that the composition of metals was last used around late 1600's to very early 1700's. no later than 1725. they went back to site and worked the cannons loose, and pushed them over, covering them with sand intending to return at a later date to try and retreive them . these cannon were in less than 20 feet of water. within two years the father was disabled and unable to return. the son ended up being a drugged out lowlife that couldn't afford to buy cigarettes much less try and retreive these. this all took place in the mid to late 70's. the area was south of daytona, though i'm not sure where. possibly someone could research where the bombing ranges were at this time and luck up on something. i have the peoples names if anyone is interested in doing this research, then you could find out the exact years he was in service and possibly where he was at this time. if anyone does and finds some of a plate fleet or something please send me a plate.