In the years after WWII, several countries experimented with general-use optical sights on service rifles. The Germans had pioneered the concept with the ZF-41 long eye relief optic during the war (and the ZF-4, to some extent), and the British actually adopted the EM-2 with a permanently-mounted 1x optical sight in 1951 (only to un-adopt it almost immediately in favor of the FAL). The US also tinkered with the idea, as demonstrated by this 1x optical sight on an M1 rifle for sale at Rock Island. I was unable to find any reference information on this type of sight, but it does seem to fit the period. Perhaps one of our readers will recognize it?
Related Articles

Prototype
Colt 607: The First AR Carbine
The Model 607 was Colt’s first attempt at a carbine version of the AR-15 rifle, shortening both the barrel and stock. The action is identical to a standard AR, but the barrel is only 10 […]

Single-shot Pistol
Rollin White’s Single Shot .38 Rimfire Pistol
Rollin White was the inventor who patented the bored-through cylinder in the US, and sold an exclusive right to this patent to Smith & Wesson. They would use it as the basis for their own […]

Submachine Guns
George Hyde’s First Submachine Gun: The Hyde Model 33
George Hyde was a gun designer who is due substantial credit, but whose name is rarely heard, because he did not end up with his name on an iconic firearm. Hyde was a German immigrant […]
Just a guess, but I imagine that “scope eye” was a signfiicant problem with this design in certain positions, but just imagine how awesome one of these would be on a .22-06 Duplex model would have been! Science freakin’ fiction!
A bit off-topic, but just happened to note this on the Yahoo feed:
http://news.yahoo.com/lady-death-wwii-sniper-film-aims-hit-russia-034543400.html
Looks like an interesting flick. Incidentally, Stephen Hunter’s most recent novel “Sniper’s Honor” (which was originally going to be called “She, Sniper”) is about a female Soviet sniper in the Ukraine. Like the rest of his books, it’s an entertaining and well-written read aimed at knowledgeable firearms enthusiasts. (which is to say there’s none of those “safety-on-the-silenced-revolver moments that makes the reader hurl the book in the trash.)
You know, that reticule is a lot like the one on the old SUSAT scopes we had on our L85’s.
Ahem… “Oh aftermarket parts designers…” Just might be something I’d like to do with one of my two M1s… sorry, no “duplex” loads! And if the reticle matched that of the EM2, well then, all the better! 😉
I’d say you’re probably right, it looks very much like an EM-2 1x scope, perhaps US Ordnance saw the EM-2’s in the late 40s and liked the idea of it. Although the EM-2’s scope doesn’t have such large elevation knobs.
I’d like to know where those adjustment knobs and mount came from. Definitely not some Basement Bubba job !