It takes a really low-mounted scope to be even as low as 2-3" high at 100 after a 25-yard sight-in. It also works OK wioth iron sightrs.
This is why some old-time gun writers advised it, but it hasn't worked all that well in a long time. Generally, with a cartridge that gets muzzle velocities in the 3000 fps range, and a typical 3-9x40 scope, the impact will be more like 4-8" high at 100 yards, depending on the scope height over bore. That's assuming the rifle really was sighted-in precisely at 25 yards.
Which is why I normally do preliminary sighting-in at 35-50 yards anymore.
