These guns were made under the Arminius name by Friedrich Pickert in Germany before WW2. Place of manufacture (Zella-Mehlis or St Basil) would help date your gun to pre- or post-1920. There were several models with slightly different configurations in calibers from .22 through .380 revolver.
The cartridge is obsolete but available on the custom-loading market. That said, the lockwork on these guns is somewhat fragile and very expensive to repair.
Your description of the stampings makes me wonder if the piece has been polished at some point. I cant tell the true color from the picture, but these guns were a subdued rust-blue color with brilliant fire-blue small parts.
Value (if not reblued with washed-out markings) would be around $250. Cut that in half with worn/obliterated markings.
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