My 1st question would be if the stock shows inletting for the rear sight boss? Based on the appearance of the roll stamping on barrel which is light, possibly the rear boss has been removed and barrel refinished? If this is the case, I would expect to see some sign of the original inletting for the sight boss. I also see what is possibly some type of rear sight base that has been added to barrel. Perhaps a previous owner decided to remove original sight boss and attach some type of aftermarket sight? Additional pictures of the subject area would help.
It sounds to me as if the barrel has been turned or ground to remove the sight boss. Have you had the barreled action out of the stock to see if the dovetail on the bottom side has been removed as well? This is where the escutcheon mounts to accept the forearm screw. Also, if you remove the rear sight you may very well find remnants of the dovetail flat that did not get removed completely. Looking at your picture of the barrel, the “MAGNUM” section of roll stamp fades out to near nothing at the rearmost part. This would indicate to me that some grinding has been done to blend in the area that was removed.