Someback, there was an alternate storage method found (by accident). A salvage outfit raised a cannon off the sea floor. Cannon had been "spiked" before being dumped overboard.
One of the brilliant salvers pried out the spike and struck a match to the touch hole. BOOM!! Seems the cannon was loaded when spiked and remained water tight.
Salvage crew had to go back down and bring it back up again. Equal and opposite reaction don't ya know.
admittedly, this had nothing to do with the OP. I just thought it was interesting.
Coffinmaker