What are they? Tool blanks?
Bruce, these are Swiss 5.6 mm blank cartridges for the “Maschinengewehr-Markiergerät”, a device used to simulate machine gun fire. The German language designation of this cartridge is “5,6 mm Markierpatrone für MM Geräte”. Regards, Fede.
Here is a previous post with excellent pictures and information posted by Harrie:
In the french part of Switzerland, this machine was called “petophone”! Many were sold in surplus stores. It is getting more and more difficult to get the ammunition, as production was stopped in the 80ies.
Small translation : pet is like fart…