It is not identical.I'm unfamiliar with the metric caliber but it is or at least seams to be very close or identical to the 500 Jeffery. I've never seen one but others have mentioned them in previous AH posts. My largest Jeffery is a 404, which pales by comparison to its' big brother. I reload for all of my rifles. If I had to buy commercial ammunition for them I doubt I'd be able to shoot very often if at all. What powder, charge weight and bullet do you use in your Schuler? (sorry there are no umlauts on my computer.)
Since the normalization at the beginning of the 21st century there are 2 cartridges , the 12,7x70 Schüler and the 500 Jeffery. Whoever buys ammunition has to be careful. My rifle was built in the late nineties before the standardization and would be rather a 500 Romey Hybrid.
I load my 500 Schüler with a 535gr FMJ bullet from Woodleigh and 127,4gr of R 904 powder from Rottweil to reach the muzzle velocity of 2400 fts.