Easy cartridge to make up from 6.5x52 Carcano brass, 7.35 Carcano brass, 6.5 MS brass.
If you have a Lathe, you can add 6.5 Jap and even .220 Swift to that list.
Factory ammo used a very small Berdan primer. The stuff sold here very often had neck splits BEFORE it was fired.
You can use 7.62x39 slugs. Powder charge is about 10% over x39. I am told they like IMR-4198 but cannot vouch for that, although it came from an excellent source.
Czech military only used the round from adoption in 1952 through replacement by the Soviet round in 1957. Most of the rifles seem to have found their way to Africa where they have been beaten to death in various wars, insurrections, rebellions, revolutions, "freedom movements" and their corresponding "anti-terrorist actions".
Good luck, Friend!