Hi FirebirdV8

You mention a rare early adjustable sight for the M39. the unfired very late model M39-2 I acquired a month or so ago came with the usual windage-only sight installed, but there was a same style mount but fully adjustable sight included in the box. It uses a tiny little tool to move a slanted screw to change the elevation, and has a white outline around the rear notch. Is this the sight you were referring to ?

Oh, and it's no longer an unfired M39-2. After a couple of magazines of FMJ through it as a bit of a break-in, and some minor windage adjustment, it shoots very tight groups right to point of aim. They are wonderful pistols!