Your rifle was made after 1908, as it shows on the receiver, (M1908).

It is marked Oesterreichischen Waffenfabrik Gesellschaft Steyr (meaning Austrian Gun Factory Steyr Ltd). The OWG was in 1926 renamed Steyr-Werke AG (i.e. the town of Steyr Works), and in 1934 to Steyr Daimler Puch, (i.e. the names of 3 amalgamated companies). This is what Wikipedia states below:

Die ÖWG wurde 1926 in Steyr-Werke AG umbenannt, welche 1934 mit der Austro-Daimler-Puchwerke A.G. zur Steyr-Daimler-Puch AG fusionierten.

So your gun was made before 1926. My 9x56 Mannlicher-Schoenauer is made in 1920 and is not marked, "Made in Austria" on the receiver. Nor is yours. However my 9.5x56 M-Sch., made in 1927 is. So that would also suggest a date between 1908 and 1926. If it is not marked "Not English Make", as you say, that brings us back a year, to 1925.

If some of the guys who have dated their rifles by the year proof mark look at their receivers, we may get an idea when the "Made in Austria" marking first appeared.

According to Gun Proof in England in Gun Digest 1977, the NP with cutlass is a London mark, 1904-
NITRO PROOVED is 1904-1955.
V with a crown is a London mark, 1637-1955.
CP with a crown, 1637-1955.
NOT ENGLISH MAKE 1925-1955.

The Voightlaender scope may have a DRP number, being the patent number. But sounds like it is an early one, so that doesn't help much.

Best I can do.