Lieferung Unbekannt , in German Ordnance Speak, means “Contents of Box from Unknown Lots” and may mean that the Package ( a repack) contains Mixed Headstamps or Cartridges of the same Headstamp, but of differing Production Lots or even Years, whilst from the same Manufacturer.
Repacking was usually the result of “clearing up” Broken Packets, Loose ammo collected from Units, Battlefield Pick-ups (salvage), packets which had lost their Labels or were damaged, etc.
BY the way, “Lot” in German is “Los”, usually abbrev. to “L.” ( as seen on packet Labels).
The Lot Number on the Cartridge Headstamp refers to the Lot of the ( empty) cartridge case Production…the Production (filling) Lot is usually different. ( Look at a Label to see the Difference.)
The Filling Lot ( which is important for Identifying when the Cartridge was actually filled, i.e., to Identify filling Problems or errors) is Part of the Label of the Packet…but if this is Lost, then the Cartridges become “Lfg Unbek”.
Usage: Such re-pack ammo was restricted to Training Use only, as its reliability was suspect. Of course, in Wartime, any ammo was better than none.