The KE-7 was a short-recoil, open-bolt light machine gun developed by SIG Neuhausen between the World Wars. It was offered for sale in basically any cartridge a nation might request, and were sold primarily to China and Latin America. I have a full Vault page on the KE-7 with a number of manuals, and today I also have these photos, from the collection of Reed Knight:
Note that the standard magazines held 25 rounds, and this gun has an extended magazine fitted. I don’t know exactly how large it is, but I would guess 40 rounds. I have not been able to find reference to these magazines in any literature.