I remember he recommended sighting in 3 inches high at 100 yards to maximize point blank range. I did for years until I realized 100 was about the maximum range I could shoot.
I used to sight all my centerfire rifles in that way, and never had a problem. Now days, I sight dead at 200, unless it's a rifle with a BDC scope. Of course, O'Connor was hunting in the West and the mountains where long shots were the rule, rather than the exception. Here where I hunt, a shot can be from pointblank to 400-500 yards, with most being in the 100-200 yard range.
