This is part of the post WW2 development for an assault rifle that was based on the 7.5×55 Swiss case. There are descriptions of these on p. 137 – 140 of the booklet Cartridge Headstamps of Switzerland 1867 – 1985 by Michael am Rhyn

   This case has a brass washed finish that identifies it as a proof loading.

    The specimen above is a grenade launching cartridge with a zinc plated brass case and a small wooden plug at the case mouth.

  This is a blank load with extended neck.

   This cartridge has a dark blue base. It is an experimental case with different anvil/primer pocket design. (Zk lager und ambosshöhe geändert)

   These specimens with the purple base are AP rounds with hardened steel core. (Harter Stke)

   Soft (not hardened) Steel core (Weicher Stke)

   Tracer

The specimens shown below from box samples are from tests done with different velocities. The first specimen with the one-quarter purple base was for a velocity of 300 m/s from test XIV/414. The second specimen with one-half purple base was for a velocity of 400 m/s from test XIV/415 and the third specimen with three-quarter purple base was for a velocity of 700 m/s from test XIV/416. (IAA Forum)

Pictures: IAA Forum