I don't know if I believe the provenance of the item but I was browsing an auction site and found a M45 scope. It caught my attention because it is mounted in a dehorned Unertl scope mount. The seller claims that it was put together by USMC armorers. I don't know if I actually believe that but it is a good story and an interesting piece. What I was curious about was whether or not it would actually function as a rifle scope, which is how the seller is describing it. My very limited research indicates that the M45 scope was intended for M3 anti-tank guns so I'm guessing the optics are capable of handling recoil but I wonder what the eye relief is. Is it long enough to safely mount onto a rifle? It would look really impressive on 1903A4.