I have had some experience reticle-ranging antelope, and i can say that it's better than guessing. I have a lot of experience reticle-ranging hard tgts. such as steel silhouettes, and bowling pins, and since the tgt. dimensions r exactly known, reticle-ranging is much better than on a tgt. that is simply approximated in dimension. But, i think if a guy put some thought into it, it could be done with a fair amt. of accuracy. There r several factors that affect reticle-ranging. They r--

1) size of tgt. relative to reticle subtension

2) magnfication and quality of scope

3) conditions

4) stability of optic

5) experience

There r 2 reasons why scope magnification is important. It allows u to more accurately define the tgt. edges to allow for a more accurate interpolation between stadia, and it can help with approximating the relative size of game (older animals tend to be bigger than younger ones), allowing the "ranger" to adjust for the size of the animal. If you're using a 2nd focal plane optic that mil-ranges @ 10X, but adjusts to 20X, then i would suggest "mil-ranging" at 20X, and double the reading (once u've confirmed that 20X is actually 1/2 of 3.6 inch per hundred yds.), for the above-stated reasons, as well as it gives u a more accurate reading since it doubles the interpolative accuracy (1/10th 3.6inch per hundred yds.= .36 IPHY---- 1/10th 1.8 IPHY= .18 IPHY). By working the mil-ranging formula backwards (reverse milling) u can get an idea of the accuracy of the system. Here's the equations for a 500 yd. 11" coyote using the std. mil subtension of 3.6IPHY--

11 x 100 / 3.6 / x = 500 yds.

x=0.6 mil reading

If the coyote is actually 10 inches, and he brackets right @ .6 mil here's the calculated error--

10 x 100 / 3.6 / .6 = 463 yds. This amts to a little less than 10% ranging error, but in this scenario a miss would occur. The biggest problem with reticle-ranging is that as range increases the inaccuracy becomes geometrically greater. But it is better than guessing, and will flat amaze u at how accurate it can be on hard tgts.