Out Of Sights

[Ron Wood]

Just to give some flippant answers: 1) They work well; 2) They were used to inflict damage or suppressive fire on opposing forces; 3) The numbers are increments of 100 meters in range to bring point of impact of a fired round to close to that range; 4) They are properly set when the point of impact is at the range of the opposing force

Now, to be more specific: The cross bar with the button is a yoke that engages the curved ramp on the sight base and slides on the ladder bar (the shiney part with the numbers on it). As the cross bar moves forward on the base, the curved ramp elevates the ladder bar. The ladder bar has a series of notches on it side that serve as a stop for the spring loaded pawl activated by the button on the cross bar...when you push the button it disengages from the notch it is currently in and re-engages a notch at the range you wish to set. The "hinge" on the front of the ladder bar is not set perpendicular to the bore but rather at a slight angle. This causes the rear of the sight to move to the left as the sight is raised...at long ranges this compensates for the drift of the bullet imparted by the right-hand twist of the rifiling.

With respect to how accurate they are...I would not want to be the recipiant of a shot fired at any range, even out at the preposterously optimistic range of 800 meters.