When the Winter War started it become immediately obvious, that the amount of concussion fuses available was way too small.  This was solved by introducing a new M/40 that was made from cartridge case of 7.62mm x 54R rifle-ammunition, about 275000 of these were made.  M/40 concussion fuses made by different manufacturers had slight differences, but all of them had the same basic structure and worked the same way.

PICTURE 3: Concussion fuse picture and structural drawing.

A = Cartridge case, B = Hammer device, C = Hammer, D = Detonator cap part, E = Hammer spring, F = Pin, G = Seal plate, H = Lid, I = Installation ears, J = Cap space, K = Seal, L = Closing screw, M = Safety pin