No surprise. I have an all-matching 1943 Izhevsk that's mechanically perfect. Bore bright and shiny with no signs of wear. I'm not the original owner, but I guarantee you that rifle either never saw service or never saw an actual battle. I also recently picked up a barreled receiver (no bolt) to repair a friend's gun that had also had a barrel in unissued-condition. In fact, I'm pretty sure that one was never used because the gunsmith who fitted it out said the chamber was tight and he had to size it slightly. Unissued Mosin actions are out there. They're just rare as hen's teeth.
The story behind my friend's gun goes, he inherited it from his father, so it's special to him, but the barrel was toast. As a Christmas present last year, I paid for a gunsmith to fit the bolt to the new receiver and install it on the gun. He's still pulling his dad's trigger, working his dad's bolt, and shouldering his dad's stock, but it's been professionally fitted with a pristine barrel and receiver.