Arjen,
i know this option, but as always no prove for it. When cases were reloaded the were marked with a dot at the edge, sometimes with or without the year of reloading. However i have a 17 cm case without reloading marks, but with EGZ and otherwise arround. The same with the theory that it applies only for naval marked cases, i found one, marked Feb 2018 with a acceptance stamp of the army. so still confused, however knowing the Germans, there should be prove somehere on paper or whatever.