Hi Fernando,
Though this is not as old as most pieces that am headed for I like your little pistol, especially the nicely constrasting blackened stock and the embossed silver inlays. Most of all, however, I admire the perfectly homgeneous surface patina.
I tend to assigning it to either Spain or Portugal, ca. 1730-50 but will look up what little I can find in my humble library (not a joke because I am not really overfed with books on Italian, Spanish and Portuguese arms). Also: I should not totally rule out Southern Italy as a possible provenance.
Best wishes,
Michael