100 yard sight zero possible?

[jmoore]

If you want to go to the trouble of lowering your point of impact 2", you'll need a 0.0176" taller front sight. (It works out to be about 0.0088" per inch of movement assuming a 31.7" sight radius and exactly 3600" to the target.)

It sounds mighty close to me! Check your load- Original 30'06 spec'ed a 150 gr flat base bullet at 2700fps out of a 1903 Springfield: I've found that the extra inch of barrel doesn't change the velocity much, if at all. A heavier bullet or a faster one could account for the slight variation you're getting.

BTW The sights do seem to be correctly regulated for me out to 600yds w/ M2 ball when the zero is right at whatever the checking distance.