According to Lee Kennett, as well as the Wirnsberger book on proofs and a chart from Stan Baker, ++ or ** is improved modified; +++ or *** is modified. And I don't believe Italy was marking the pressure in bars or kg on their guns at that time. Rather, you'd have either a single star in a circle for standard proof; two stars in circle (over PSF, in both cases) for superior or reinforced proof.

Brent, I'll send you a pm for someone in that part of IA to look at your gun.