Note that the quench of case-hardened parts was in oil, not water. The result was a dark mottled gray/black surface, not bright colors. With time and handling this often fades to a light mottled "silvery" appearance. (Bolts were polished bright after the quench, apparently.)

In contrast, parts "browned" (rust-blued) at overhaul have a uniform black (or blue-black) finish without much/any mottling. It is significantly more durable in use than the original oil-quenched finish, frequently remaining quite dark after 100+ years.

Since the "browning" process can be done by any competent tinkerer with a metal tank long enough to boil the barreled action in water, it's sometimes near impossible to tell if a decent rust-blue job was performed post-service. Often the main clue is that many would-be restorers can't resist the temptation to polish/buff surfaces far more than the armory did.