I had always heard of the 25 yd theory, but it was for a zero at 200 yds. Supposedly the fired round that bulls eyed at 25yds would be high at 100, then back down at 200.
Just a theory I read somewhere.
I'm sure that this is correct if certain ballistic parameters are met, but is not a hard and fast rule. I usually, when having just put a rig together, will sight in initially at 25 yards, striving for a POI about .5" to .25" low, and even then typically find it a tad high at 100 yards.
I will usually sight 1.5" to 1.75" high at 100 yards due to the huge majority of my shots being under 50 yards, but an occasional opportuinity may arise for no more than 300. And those are rare.
As far as BC's, I can get a better idea of what the true ballistic coefficient is by chronoing at two known ranges.
Zeroing and shooting at the ranges you will hunting at is what my experience has led me to believe is the best method. Sometimes those bullets are not so predictable.
