The "High Velocity" here does not refer to the load. Instead, the Mannlicher-Schoenauer 1925 model with the longer magazine to take cartridges up to 80 mm = 3.15" oal like 7x64, 8x60, .30-06 or 9.3x62 was often called the "High Velocity Model" or "Hochrasanz-Repetierbüchse" in contemporary Steyr catalogs. At least, there is no hint to a special load or sighting visible on the rifle.

But there were indeed German 9.3x62 "high velocity" loads in the 1930s, sometimes even called "Magnum" then.
While the "standard", traditional load was a 285 gr bullet at about 2345 fps, DWM also offered a 231 gr psp at 2540 fps and a 262 gr strong jacket at 2525 fps. RWS had a 258 gr H-jacket at 2697 fps.

Taylor in "African Rifles and Cartridges" complained about these offerings, quote:
"But I cannot see that there was any necessity for boosting the velocity of this cartridge; on the contrary, without widely advertising the fact they intended to do so, I reckoned it unfair on, and even dangerous for, the thousands of users of this shell, most of whom could not read German even if the new ballistics were quoted on the boxes of shells."
Another classic case of an Englishman not understanding metric numbers. At least bullet weight and type + powder charge were noted on the then 10 shot German boxes.