If you look very carefully at the photo steelcharge linked to in the "Russian Carronade"/swivel post, in the lower right hand corner there's the muzzle of a mortar with the same band just in front of the "extra-thick" belly band (which is just visible in the very corner).
I realize it's hard to prove this without more evidence, but perhaps this Russian mortar and the swivel gun in the previous post are the very same battery mates shown in the photo, reunited after 160 years? Food for thought, anyway!