Man, that's rough. So you basically stripped it down to bare metal? @norag38 is right, vinegar is way too aggressive for old bluing. For light rust on a finish, I use a brass brush and some gun oil, scrubbing real gentle. If it's a bit worse, 0000 steel wool soaked in oil can work, but you have to be patient and check constantly. The goal is to break up the rust without cutting into the good bluing around it. Anything acidic is going to win that fight every time.