I was very skeptical when I first heard that Leupold was selected to supply the USMC with their Mark 8 1.1-8x24mm CQBSS scope for use on .50 BMG M2 and 40mm Mk19. machine guns. The CQBSS is an impressive scope but was designed for sniper or DM rifles, not heavy machine guns.
As it turns out, the scope is only half the story. They developed a sophisticated mount that holds the CQBSS as well as an EOTech holographic sight side by side, and still allows the use of iron sights. Also, it looks like the entire mount can be adjusted for range by the operator. Genius!
This mount also solves the problem many of your pointed out a few weeks ago when I blogged about Raytheon ELCAN SpecterHR and SpecterDR. Because the SpecterDR is mounted on top of the SpecterHR, the operator needs to put his head up high to use it, putting himself at greater risk of being shot. Mounting the holographic scope and optical scope side by side solves this problem.
[ Many thanks to TenPoundMonkey for photos and info. ]