altimeter calibration

[skwinty]

gravity32,
have a look at this boeing 757 bulletin.

"
The amount of undershoot or overshoot depends on the amount of the barometric correction, when the altimeter is reset, and the elapsed time from altimeter reset to level-off. "

It may help you a bit in your quest.

Boeing 757 Boeing Bulletins :: FMC-16 : FMC VNAV Anomaly During Intermediate Level Off