Good detective work ! Agreed, the stuff I have is #23 as well, the light grey coloured primer and 4 stake marks are very distinctive.
"23. no headstamp, steel primer, by Povázské Strojárne, Povázská Bystrica, Czech."
I'm curious when it was produced as it looks to be in very good condition, very little tarnish, compared to some 1950's era Czech 8mm on chargers that I have. No doubt storage conditions will greatly affect appearance but it looks much "newer" than 1950's ammo.
