Though standard factory barrel lengths of the M1910 were 50 cm = 20" for the full stocked Stutzen carbine and 60 cm = 23 ½" for the half stocked rifle, other barrel lengths were listed as availble to order. So half stock Mannlicher-Schoenauers with carbine length barrels come up from time to time and confuse so called "experts". Here are some photos of my own M1910, same configuration, 20" barrel and half "rifle" stock, like your's.

M1910s usually came with the typical M-Sch "butterknife" bolt handle.

If your bolt was with the rifle when it was German proofed in 1927, there must be a crown/U proofmark again on top of the bolthandle root. If not, your bolt has been replaced since then.
To me the bolt now on your rifle, with the solid round knob and the flute in the guide rail, looks very much like a M-Sch M1900 one. Here is a photo of my M1900 bolt in my M1910 action.