7.62x45 bxn headstamp

What is the meaning of the dash to the right of “bxn”?

The dash = one external flash hole (Berdan primer), star = brass case.
This is the first year of official production Mod.52 samples cal. 7,62x45. The cases with year 1950 or 51 (experimental mod. Z-50) are predecessors of Mod.52 cartridges. They had the same dimensions and performance that Mod.52. Completely first samples were in cal. 7,62x45 with smaller diameter of case - year of production 1946, but diam. of bullet was 7,74mm.
Next experim. 7,5mm cartridges mod.Z-47 (or Z-49), year of production 1947-1949 were made with fatter case. Diameters of base are: 11,3mm Mod.52, 10,7mm Z-49, 10,3mm Mod.1946.

So they basically follow the German WWII system. Why are they so jumpy about the headstamp right in the beginning of 1952 when they need to be settled on the final official version of VZ52? I assume the lack of that dash means 2 flash holes.

Yes,you are right. Samples without dash are with 2 flash holes. The same system was used in steel cases too.