I guess it could be an updated barrel, or it may not have been engraved when it first left the shop and that was put on later when it came in for cleaning, service or trade-in. I wouldn't know without going through 40+ years of day-books. I have the books, I'm not doing the research! The rear and front sights appear to be original and it does have a 'slide-up' peep sight. It's just not in the pictures.