There has been until the 1980's several government plants/arsenals in France, in charge of producing/repairing military weapons and ammunition. The major ones were the "Manufacture d'Armes de Saint Etienne" (acronym "MAS", as in rifles MAS 36, MAS 49, MAS 49/56, etc.), the "Manufacture d'Armes de Chātellerault" (acronym "MAC", as in the 9mm pistol MAC 50), the "Manufacture d'Armes de Tulle" (acronym "MAT", as in the 9mm submachine-gun MAT 49), and the Manufacture d'Armes de Biarritz (acronym "MAB"). All these arsenals were progressively closed one after another after the French government started outsourcing weapons/ammunition purchase and as the volume of the Forces progressively decreased (end of colonial wars from the early 60's; collapse of the Warsaw Pact from the early 1990's, change from draft to professional armed forces, etc.).

The Chātellerault Mauser is probably an ex German Mauser that was either refurbished or re-barelled at the "MAC" and stamped "Manufacture d'Armes de Chātellerault". The French Armed Forces used a lot of German weapons in the immediate post-WW2, until national production resumed in the early 50's, as well as they recruited a lot of experienced German ex-military people who joined the French Foreign Legion from 1945.

Louis