Agree with flabigpapa that it is an aftermarket engraving job. Nice enough for sure. The serial number is a mystery. There was no avenue for anyone (except perhaps a high-level manager, CEO type in Remington) to order a particular serial number. And as noted, if it would have been through the Custom Shop for engraving, there would not have been the heavy roll mark 'engraving' on the receiver. The gold birds obviously were put in on top of the factory roll mark. Perhaps the serial number was not noted in time to stop the roll being added, someone noticed and then requested the purchase. No real way to tell unless the Custom Shop has a record. In any event I do not believe the engraving was done in Ilion, but could be wrong.
If you call Remington, they can tell you when it was made, but unless there is some other record, that is all that can be determined.
Scott Hanes