Ah, well, if they were certainly
German rounds (rimless, 7.92x57) they probably wouldn't have worked in their light machine guns, because I think they were recoil rather than gas-operated. So they may have been 'ersatz' bullets or grenade blanks - see here:-
eBay Forums: Wooden bullet Tip ...
Vot iss zis Cherman smell of vich you speak..?
Regards,
MikB