What really sets the newer versions of the ART system apart from the military ART models of the 1960's is the cam system which automatically allows for the trajectory of the round being shot. Let's face it, the original ART scopes were set up to allow tactical shooters to keep hits on a man-sized target out to around 600 yards ... shooting rifles chambered for the U.S. military rifle cartridges of the time - the 5.56x45mm NATO (.223 Remington) and the 7.62x51mm NATO (.308 Winchester).
The Hi-LuxM40 scope is very true to the original scope used by the Marine Corps. For years, many tactical shooters have wanted to build a clone of the 1960's M40 sniper rifles. Remington even came out with an M40 version of the Model 700 center-fire rifle, in .308 Winchester, a few years back ... but there simply was not a proper scope in production.