Early post WW2 Czechoslovak experimental rifle cartridges

A few years ago I found a handful of badly corroded Czech experimental rifle cartridges, which remind of the later 7,62x45 vz.52. They are all brass cased and it looks like the steel jacket bullets were all Tombak, not Nickel coated. Because of the bad condition the bunch finds itself in I would not swear if they all are the same calibre. In spite of being made by Pova