I believe it will be a long shot finding any once-fired 22 CM brass. Manufacturer's don't yet offer this chambering as 'factory' ammo. A few offer brass for this round but I doubt anyone has much interest in selling their once-fired brass after fireforming to their guns chamber, as they will likely load it again.
You can find 6 and 6.5 CM once-fired as it was a round loaded at the factory and the shooter may not handload themselves, hence they have available brass to sell.
Good luck!