I knew I'd seen one before!
It's a Bodeo revolver. Invented by Italian gunsmith Carlo Bodeo (from Naples) and adopted by the army and police forces to replace the older Chamelot-Delvigne adopted in 1874. The Bodeo, patented in December 1886, was adopted as "Pistola a Rotazione Sistem Bodeo, Modello 1889".
It served for a very long time, up until the start of WW II when it started to be replaced by Beretta semiautomatic pistols.
It was chambered in 10,35mm.
There were three versions: the first one had no trigger guard and was known as "troop revolver", the second version was made from 1891 onwards and was known as "officer's revolver" it had a trigger guard, and finally there was a "reduced" or "compact" version which had a shorter round barrel (this is the type you have).
It was manufactured by lots of factories, from the Regia Fábrica de Armas de Brescia to the Castelli, MIDA, Glisenti, Beretta and Bernardelli factories among others. During WW I some were made in Eibar (Pais Vasco, Spain).
The troops called them "coscia d'agnello" (lamb's leg).
Here's a pic of a Spanish made "troop revolver" Bodeo (no trigger guard and hexagonal barrell). Yours is in fantastic shape.