bogart:
I believe there used to be three companies which sold firearms under the "Liberty" banner -- one based in Montrose, California, another in West Chester, Pennsylvania, and a third in Spain. The Montrose company operated under the name of "Liberty Arms Corp.," and imported inexpensive firearms from West Germany and Italy back in the 1950s. Those guns, I believe, were actually manufactured by such firms as Rohm, Herbert Schmidt, and Reck Firearms. Your derringer would appear to be one of those guns.
Due to its lineage, the derringer will have great sentimental value for you personally. Otherwise, the "Liberty" guns don't seem to be in much demand on the collectable market. If it were mine, I would simply keep it as a family heirloom. I also might not want to subject it very much to the pressures of modern-day ammunition.
Good luck to you.
[size=10]Edit: Typos.[/size]