Signal gun or failed experiment?
 

I acquired this piece several years ago and, while it is outside my usual interests, I found it compelling enough to add to the collection. I'm hoping some of the gunnery experts on this forum can tell me what it is. I presume it's a signal gun but, for all that I know, it could be a DIYer's failed attempt at barrel casting.

It measures 16 inches from cascabel (button) to mouth and has a 1-inch diameter bore, which has been sleeved with ferrous metal (iron, steel?) reducing the bore diameter to 13/16". The bore length is 12 inches. The width at the outer ends of the trunnions is 7 1/4", while the width of the barrel at its widest is 3". The gun weighs approximately 22 pounds. There appears to be a vent on the top side (highlighted with a red circle in the image provided), which is filled with sediment. The gun bears no discernable stamps or marks.

The seller told me he had recovered the gun in 1949 from the bottom of a navigable Midwestern US river where shipping was known to have been active from the early 1800s. At the time I acquired it, I did some low-level research about the the decay of bronze artifacts subjected to fresh water immersion and, IIRC, it seems there is some basis to think the pin holes that cover the gun are the result of immersion for many years (the river in question is known for its high tannin content). As seen in the photos, the metal is heavily patinated.

I'm happy to shoot additional photos or answer any questions you may have. Thanks in advance.

Very nice piece! No expert here, but from the pics, it appears to be a legit cannon of small bore, probably early/mid-19th c. Despite its small size, it might still fit into the swivel gun category. Are the trunions located mid-barrel, or closer to the 'bottom' of the piece on one side to allow for sharp angling? In Gilkerson's 'Boarders Away II', there's a small 16" piece with 3/4" bore that is a true swivel/rail gun. I'll wait to see what those more knowledgeable have to say.

Thanks for your reply. The trunnions are placed approximately mid-barrel, but . . .

. . . I discovered that the bottom of the barrel has additional reinforcement (thickness) in the area shown by the red box in the attached image. This "pad" slopes from the rear of the barrel to the front, where it abruptly stops, forming a well-defined edge (indicated by the yellow line). The highest point on this edge stands about 1/8" proud of the rest of the barrel.

I can't imagine what purpose this served other than reinforcement, but then you would think it would have been all the way around the barrel, not just a small pad on the bottom.

Maybe the sloped pad was part of the elevation mechanism, which I assume would have been little more than a wedge that moved fore and aft on the pad to raise or lower the barrel.

Very interesting! es, it does does sound like it was cast in this way to direct the barrel in an upwards direction. With the trunnions being level and this thickened bottom reinforcement to slant the barrel upwards, I'm leaning towards a signal gun. Again, little more than a novice here. I was hoping some others might still come in on this one with their opinions.

Mr. Google seems to imply that cannon were not unusual on flatboats and keelboats; probably to deter Indian attacks and or river pirates.
The lining may have been inserted due to the brass becoming 'honeycombed' with age and use.

There are a lot of Southeast Asian cannon that are being made today with inserts like this but are being sold as old.

I wonder if this is a recent make, due to this and the holes I see on the outside, as well as the touch hole that is too crisp around the edges.

These are my musings.

It's a Swivel Gun (by the looks of it 18th c. french naval if authentic). A small caliber anti-personnel cannon (sometimes musket) primarily for warships and merchant vessels. An old bronze one like that would have originally been mounted to a U shaped yoke via those trunions. This would allow it to pivot on the vertical axis. And the long round rod coming off the bottom of that yoke would be dropped into a hole in a ships rails or Bulwarks (sometimes even on crows nests). This would allow it to pivot on the horizontal axis. That knob on the back. That's what you'd toggle and stabilize it by (yeah...Unfortunately with your hand on the early ones).

These would mostly be positioned fore an aft on a ship, in case of close pursuit or a crossing the T maneuver. If the sailor manning it was on his game and a little lucky. He'd have a good chance at taking out a crucial member of an enemy crew.

You might actually want to make sure it isn't still loaded. They were generally kept loaded. As when it was time to put it into action. there wasn't time to load or reload it considering the very specific circumstances of it's use. You had one shot pretty much. And you had to try to make it count. That could be an old fuse in the touch hole and not corrosion. It would be flush fused to insure getting a quick shot off.

if a keel boat gun, may have been loaded with a charge of musket or pistol balls as a large shotgun for repelling boarders. would bronze corrode in fresh water,
and likely covered in sediment restricting oxygen availability, like that in a couple of hundred years? 2000 yr. old roman bronze artifacts are usually in better shape. if it were galvanic corrosion based on the steel bore insert, i suspect that the iron would have gone before the bronze.

i recall reading here about small indonesian cannon (lantaka) that turned out to be bronze or brass sheet over a concrete core with a iron or brass pipe bore. caveat emptor.

Only reason to line the bore is they didn't trust the brass casting.
No period cannons were made of brass with iron/steel bore liners.
I would say a relatively modern piece that has corroded.
I built a similar one using an unknown iron casting and having a seamless stainless steel tube hydraulically press fit into the bore.