Certainly a very early M1905 as another one in the 1000 range was proofed in 1907.
Early Mannlicher-Schoenauers without Austrian proofs are not uncommon. Gun proof then was to protect the domestic customers. There was little mutual acceptance of foreign proofs then. Austria did not accept German proofs and vice versa. All Rigby Mausers were proofed in England again, though they all were already proofed in Germany. So before 1911 Austrian guns made for export did not need to visit the Vienna proofhouse first. Alas, they were to be proofed in the importing country anyhow, if proof was mandatory there.
Those +/- numbers were for fitting receiver and barrel threads. The circled letters, here V and T (or two Ls back to back?) were personal marks of Steyr factory inspectors, found on all Steyr made guns, commercial and military.