You do have a couple of odd bits in there that seem to be the result of awkward translation, at least from a U.S. point of view (The MS reflects a 'high level of resistance'...).

The barrels were available in various lengths across the pre WW2 MS models.

Between the M1910 and the 1950 there was the 'other prewar MS', the M1924 'Sequoia'. Originally made for export to the U.S. and chambered in .30-'06, the M1924 had a longer action and magazine. Unsold 'Sequoia' rifles and carbines were changed to chamberings more popular in Europe, and production continued in various calibers (a departure from the previous proprietary and 'model specific' M1903, '05, '08, '10). Stoeger sold them as the 'High Velocity' model in various chamberings including the coveted 10.75X68. Collectors of today often refer to them as 'M1925'.

From 1939 Stoeger Catalog:

You've got some great information, just needs a good edit and some 'massaging' (IMO).

Here's some additional info from MCA (Mannlicher Collectors Assoc.): MCA