On the Elcan Specter DR reticle in the lower left corner there is a range-finder that is scaled to 30” at 100 meter distances (300 to 600).

Is there a reason 30” was chosen? Is that upper torso height? What 30” common item is generally used to determine range?

An E silhouette is about 18x36", so that's reasonable.

This is the approximate average height from waist to the top of the head. It also corresponds roughly with the average car tire.

Note that you can also use the circular area fire marks for closer range use; since they are 70" at their listed distance, they measure 35" at half that distance (so the 800m circle is 35" at 400m, for example). This might potentially be useful for ranging targets in the prone, or just when convenient.

Great to know. Thanks for the help!

19x30 is the rounded figure most people use for ranging.

Those circles are why I prefer the civilian reticle over the military one.