Originally Posted by Mule Deer
Apparently they still teach the 25-yard (or actually, meters) sight-in at the South Africa professional hunter school. Or at least I have hunted with at least 2 PH's in RSA that insisted on the 25-yard/meter sight-in and that's what they told me they were taught.

One of them was quite arrogaant about it too, especially when I insisted that I shot my rifle at 100 yards too. Turned out it was 7" high. He was astonished, because he had never checked it before....


I have seen the same thing too in my rifles (not been to Africa yet, so I can't comment on PH's). Some of my rifles when sighted in at 25 yards are anywhere from 5 to 8 inches high at 100. The higher the scope mounts, the worse it becomes. Given this and your comments that "that very few scopes are only 1.5" over the bore anymore" I ran some calculations on my RCBS ballistics program. I just picked a 150 gr Hornady .308 at 2800 fps. Setting the sight height to 1.5 inches, the program predicts 2.6 inches high at 100 yards for a 25 yard zero. If you set the sight height to 3 inches, the program predicts 7 inches high at 100 yards with a 25 yard zero. A 2.5 inch height yields 5.5 inches high at 100, while a 2.0 inch height yields 4 inches high at 100. I decided to plot sight height versus predicted 100 yard point of impact.
As you can see, the relationship is linear.
[Linked Image]

As you might expect, the predicted POI will vary as a function of velocity. While there may be some minor error involved in the predicted POI (+- a few tenths), this graph largely reflects my experiences.

Last edited by Huntaria_Setters; 01/02/10.