Basic generic swivel guns, like these.
or the breech loading kind
Not very useful of itself, but great for model landing boats, elephant mountings, and similar customization. Beloved of pirates, of course.
I'm very interested in getting some swivel guns.
I don't know if anyone else has seen them, but there exists a kind of swivel gun alarm clock sundial. A graticulated base plate of sturdy bronze is screwed onto the balustrade outside the bedroom; on this is mounted a swiveling gnomon with a small burning glass attached. You do some calculations based on the time you want to get up and the time of year, and move the gnomon to the correct position, and the following morning the sunlight passing through the lens touches off a little gun also mounted on the plate, waking you with the shot and possibly wounding the chambermaid bringing you your morning cup of chocolate. Alternately, it's a cloudy day, the gun doesn't fire, and you're still snoring when the Empress arrives to call.
I've seen one in situ at Vranov castle, Moravia; subsequently a couple of others in Italian museums,
A version of same.
:ar! So that be what you're after, ha harr!