First, there is no connection between that revolver and your father's naval service. It is a Spanish revolver, of the kind imported into the U.S. in the 1920's and 1930's, and sold for a couple of dollars. They were made of cheap cast iron and I have seen several blown up.
As an heirloom, it has some sentimental value, but the dollar value is minimal and the gun is not worth spending time or money on even if parts could be obtained and anyone found willing to work on it. Most gunsmiths will not work on those guns for the simple reason that if a gunsmith fixes it so it works, then it blows up and someone is injured, the gunsmith could be liable.
I suggest you deactivate it by grinding off the firing pin, then hang it on the wall.