Axel would mean the "Schiesstechnisches Handbuch für Jäger und Schützen" by RWS. I have the second 1940 Edition but the first edition could be made in 1934.

"No, a CIP maximum pressure existed from 1940 on only. Until 1939 the gunmaker could specify the factory load his gun was to be proofed for. "

yes I know, this was simplified to make it easy and short. this so called "magnum" loads are close enough to today maximum load that I see no real difference. if they realy exceed today CIP maximum? hard to know because pressure proof today with original and very old ammo would not been trustworthy. old catalog data is to be taken with a bucket of salt. nobody had a chrony then to measure what realy happen in his rifle with a 60 cm long barrel. today you find ammo from time to time, CIP proofed, still a little bit over maximum and it got the proof mark. yes it happen and it don't make rifles explode, its allmost ever mistakes or careless handloads when the rife is in good shape. so, if the "Magnum" load was realy over reasonable pressure they could not sell it on an open market and I believe a reputable firm like RWS or DWM would have never sold a cartridge you can load in any rifle where it would not been safe under any circumstances.
thats what I mean, sorry for don't speak clear.