What is the chambering of your stutzen?

The 'Crown BNP' proof on your bolt is from the Birmingham Proof House and dates 1954 or later.

Your receiver was manufactured no later than 1926 - 27, as the 'Oesterr. Waffenfabr. ges. -Steyr' roll marking was changed to 'Steyrer - Werke AG' at that time.

https://www.steyr-mannlicher.com/en/company/

The stock is of the early style with rounded grip (most have a flattish grip with steel or horn grip cap. An available 'cost option' of the pre-WW2 years was a removable horn cap which housed extra sight beads.

The M1900 was the original Mannlicher Schoenauer as introduced at the 1900 World's Fair. From what I have read, George Gibbs then became the sole importer of MS actions to British gunmakers. Those manufactured prior to the Greek military contract (1903) were roll stamped 'M1900' on the front receiver ring, as the later commercial MS were marked 'M1903, M1905, M1908, M1910, M1924'. Some sources say the early Gibbs imports were bare actions, some say barreled, some say that they were in a 'blocked', or inletted and semi finished stock.

If yours is a pre - 1903 MS it may be rather 'special', even with the damage. You may wish to carefully disassemble and look for the earliest proofs. My impression is that this may be an early British 'custom' which has seen modifications / reproofing since.

This is a novice opinion, as I am certainly not an expert.