Pete,
You are getting confused by math. An inch at 100 yards is equivalent to 1/4" at 25. A rifle 7" high at 100 should be sighted-in 1.75" low at 25 to be dead-on at 100.
In reality there will even be some variation, because of recoil, barrel "flip" and other factors.
The rifle in question was a .375 H&H Ruger No. 1.
