Sounds like a standard Mle 1873 French Ordnance revolver in 11mm.
Mine was manufactured in 1873.
MAS is simply an acronym for Manufacture d'armes de Saint-Étienne, where these guns were made by the French government.
The lockwork is a Chamelot-Delvigne design, which was probably the first truly successful, truly reliable double action designs anywhere -- simple, reliable and quite robust.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.