7х57 Mauser case with headstamp MG 10

Picture below show the base of the 7x57 Mauser fired case with headstamp MG 10
As far I know, this case was produced for Republicans during Spanish Civil War and MG is abbreviation of the Ministerio de Guerra

Who was the manufacturer of this case (or cartridge)?
What is a meaning of digits 10 in this headstamp?

Thanks for any help

Hello, really, this cartridge is made by the republican government during the Spanish Civil war. The number 10 is the code assigned to the factory (also it exists with n º 23, to see attached photo) and the initials MG seem to mean " Ministerio de la Guerra “ (Department of the War).
The republican government on having lost Toledo to the beginning of the Civil war, was not having any of the factories ammunition and it created, across the Armament Subsecretary, it completes one and very dispersed network of factories.
A codification was in use to the Soviet style.
It is not known where they were located you are two factories.

Thank you very much, ximo, for your comments!