A pair of guns is soldered onto a central support with a bit of thick copper wire as a pivot. Only solder the outside of the guns if you want them to move!
If you clip the guns together during soldering, they will be quite stiff and will stay in position.
Here is how we will mount the guns in the tubs. The thin brass sheet shown on the plan is cut and bent as shown. You may need to adjust the size depending on your gun tub...
Here is how it fits. Adjust the bends on the brass so that the square slot is exactly the size of the gun mount, while the brass tube is a snug fit in your tub.
To make the rim of the gun mount, we snip the brass all around the rim, to a depth of about 0.1"....
Then just solder the overlapping section...
Now add a thick copper wire ring to the mount. If you only have thin wire, add two...
The guns need a second connection to hold them parallel. Here is a thinner bit of wire which can be the cocking lever.
A simple pair of handles has also been added.
... and run a lot of solder around the ring. Everything will fill up quite nicely.
Given the cost of solder, this might be the most expensive activity on the boat! I suppose epoxy or filler would do just as well....
...and add the gun mount, with the guns just above the level of the brass.