Now I was never a Marine sniper, but had the honor of serving with some terrific guys who were, and I managed a little trigger time with the good old M40A1 rifle back then. It's worth noting that through the 1980's and 1990's the Marines were well served by a 10x Unertl scope with a bullet drop compensator. Not MOA adjustments, but a BDC, set up to work with their 7.62 sniper ammo. It could of course be adjusted a bit for elevation, and had mil dots for ranging purposes. It's been 20+ years since I used one, but it worked well. Range a target 600 yards distant, dial the scope to 600, dope the wind, and press. Hits were usually pretty darned good.
A little more info from the U.S. Optics web site:
"The MST-100 and MST-150 were developed in the mid seventies by John Unertl in Mars, Pennsylvania for the USMC. These scopes were primarily built for the M40A1 .308 rifle, but were later also made for the .50BMG. Durability was a primary goal, so the complete scope housing and knobs were made from 1018 steel. The elevation knob was design with an integral BDC for the M118LR ammunition, the veneer ring below the main knob adjusts for 1/2MOA deviation from the BDC setting."
Personally these days I use Leupold scopes with MOA turrets for my long range rifles, but John Burns is in good company with a BDC approach. I haven't kept up with what kind of adjustments today's Marine Snipers have on their rifles, and am sure it's an improvement over the old BDC on the Unertl, but they managed some impressive shooting with the old BDC scope.
