Hi Aldo,
during the WW2 there was the 18th Reg Bersaglieri but not the 13th, but observing better the flash could also belong to a Regiment of the Guardia di Finanza, the flash was very similar the difference was in the form of the flame: a little more moved to the right for the Bersaglieri, and more straight up for the Guardia di Finanza.

Regards