The lack of a circle C proof behind the triggerguard indicates the stock was not on the rifle when it was proofed. In addition to the excellent information provided by Cosine26 I will mention that the 1942 Shooter's Bible lists exact replicas of the NRA Sporter stock for sale. I am surprised that no one has mentioned the lack of a serial number etched on the top of the bolt. I can't see one in the photos. On later NRA Sporters the serial number of the rifle was on the bottom of the bolt. The serial number of #1270388 should be on top of the bolt. The WL3 bolt should be correct for the rifle. Perhaps a replacement bolt was obtained also. I would certainly leave the rifle as it is an obtain the SRS sales letter. I have a 1922M1 that the SRS letter shows as having been sold as a barreled receiver.