As far as I know, they had a huge mail-order business, selling not only guns, but other mechanical merchandize like sewing machines, bicycles, etc. Yes, they're German. Before 1939, they sent goods to any point on the planet (including USSR). They were located in what became West Germany after WWII, and most of their firearms suppliers were in the East, they had to quit this line, (although one forum member mentioned seeing post WWII police handguns marked GECO.

Russian Hunting Shotguns