Chamber pin for FIE 38 revolver

This gun shows up as a QFI RP revolver in the 1992 Stoegers catalog.
It probably was made by Weirauch or Pickert in Germany.
Stoeger might help you with the cylinder pin. You could try a Colt SAA cylinder pin since these companies also made SAA copies, or a gunsmith could easily machine you one from a high strength bolt.