That is certainly a Garrucha.
I had a friend from Uraguay and he talked about the local scene and firearms etc. Great guy.
So this is a south American 'Derringer' in various calibers including shotgun
Looks like a worn version of this or this is a modern copy of the design.
The picture is an example of the type, a Rossi double barrel hammer pistol in 22
These are called Garruchas.
The Garrucha is a small pistol, similar to a derringer, common in southern Brazil and Argentina in the early 20th Century.
It is usually double-barreled,though with the barrels side-by-side rather than vertical as is common in American derringers, and the bores can be rifled or smooth.
In Brazil, the most popular chamberings were for the .320 and .380 centrefire cartridges, similar to the .32 S&W and .38 S&W in appearance, but conical.
They were also chambered for the .22 Short, .22 Long, .22 Long Rifle, and the .32, 8mm, and 9mm Flobert cartridges, among others.
These types of pistols were popular from 1930-1960 due to their low cost and small size, and were associated with the gauchos (cowboys) of the South American pampas.
In Brazil, Garruchas were produced by Castelo, Rossi, and Lerap