I was extremely lucky this week and was able to purchase another original USMC M40, but this one was signed by Carlos Hathcock during an event in 1992!
Here's my 2 M40's, the top one is Major Dick Culver's rifle, the bottom one is the rifle I just acquired:
All matching serial numbers and a 7.62 NATO marked barrel. The location of the markings on the scope and base are odd, I've never seen these parts engraved in these locations on early 6 digit rifles. I've also never seen a 7.62 marked barrel on a 221xxx serial number range rifle either. This could either be an anomaly or a rebuilt gun, I'll be spending a lot of time trying to figure this one out! Either way, the parts are all original and the receiver is original. There are specific characteristics to look for in the receiver and it would be extremely difficult to fake even if you knew what to look for.
Here's a close up of the signature:
Here's a link to the original listing if you want to see what other items came with the rifle, some better photos and a short video of Carlos signing the rifle: