The original rifles in the Czech 7.62 x 45 are not exactly common. Ammo for those beasties was never common outside the old Czechoslovakiaicon or some of their middle eastern clients; Syria springs to mind.

The later Vz 52 / 57 in 7.62 x 39 is even scarcer. being chambered for "global" ammo meant that from the start, they were on the "run til fail" track, especially in the hands of some of the "interesting people who received them. It was only about a year later that the Czechs fielded the similarly eccentric, but very nice Vz 58, thus easily keeping up with their eastern Bloc "cousins" whilst maintaining a vestige of "national identity".

If you get the dies, cases are fairly easy to form, (as long as you like bulk trimming and neck reaming), from 6.5 Carcano or 6.5 x 54 MS brass. Any .308” - .311”, 125-130 gn spire-point should work OK. If you can find bulk "pulled" 7.62 x 39 "military" (ball) bullets, they work fine as well. Start with recommended propellant loads for 7.62 x 39 and experiment.

If you like a challenge and have original ammo in bulk (good luck), as I recall it takes the standard "European" Berdan rifle primer; as per RWS 5608 ("Mil-Spec" and VERY hard to find) or RWS 5627 ( thinner cup and not quite as hard to find). Some of the "majors" have apparently made limited runs of the dies in the past. They may be expensive, but them's the breaks.

If you find a collector who is willing to swap a Vz 52/57 (7.62 x 39) for your original 52, you can save a lot of effort if you want a "shooter" that is a bit "different".

Have fun!