I have seen a number of pictures here on the hide of precision rifle scopes that appear to have another red-dot, or holographic aiming devise mounted on the precision scope. Is this for rapid acquisition in the sight picture of a long range target then shifting to the precision scope? Who makes the more popular variances? An example is on the sample video clip of "setting up the rifle" by Frank Galli. I would post the pic here but I am not sure how to do that.