I haven't been able to find any really solid information on anyone firing it. From an International Ammunition Association Forum post, it sounds like the Czech firm Považské Strojarne (aym) set it up for the Ethiopians.
For the price Sam is advertising at the moment, I'd just go with the PPU M1 ammo. The only reason I can see for buying 50 year old surplus of unknown storage provenance is for the en bloc clips, so unless you need those I'd go with fresh modern boxer-primed brass-case ammo.