Steve:
Polished receiver rails would be in the white, as opposed to blued. The polishing could be considered to be somewhat coarse, as opposed to a mirror finish.
National Match, Sporter, and Heavy Barrel Target Rifle bolts were polished in a very distinctive fashion, once you have seen a few, you will recognize them. Think of coarsely polishing the bolt lengthwise, then finely polishing the bolt in a circular fashion. The areas around the locking lugs and safety lug will show small areas of lengthwise coarse polishing, while the rest is finely polished. This is one of the best ways to identify an NM or Sporter bolt.
Then, at some point that escapes me at the moment, SA started electro penciling the serial number on the bolt.
By the way, the bolt should (most likely) have WL3 (in a triangular fashion) on the root of the bolt handle.
HTH
