<center><img src="http://img.slate.com/media/1/2057072/122963/2122850/2129812/051108_life_jarhead_TN.jpg"></center><p>(scene from Jarhead)

I guess it could reduce reflections that could give away your position, but is a scope even usable with such a small slit?

Russian folklore....but a glint off a scope gives you away. but today's modern optics reduce that.

as long as you can see a few crosshairs....but the big head with the back cap behind the scope makes a good target.