.223 ballistic mystery...

[bellavite1]

Please guys help me understand because this is driving me nuts:
It is common knowledge that a .223 chambered ar, zeroed at 50 will somewhat, depending upon load, have a second zero at about 200/220 yds.
Because of said trajectory it will hit approximately 1.5" high at 100 yds.
This also matches my ballistic calculator figures (1.4", but close enough).
So why do my rounds hit consistently 2.5" high at 100 yds?
Now, the lack of accuracy of my rifle is becoming legendary, but I doubt that is the problem here...

Scope height is 2.6"
Hornady 62gr
Velocity should be around 2940 fps