A disk drive and related methods are provided for tuning the control of an actuator for position mode seeking of a head between tracks on a disk based on a measured open loop response of the actuator. The disk drive includes a rotatable data storage disk, a head, an actuator, and a servo controller. The actuator positions the head relative to the disk responsive to a current command signal. The servo controller carries out a position mode seek of the head between tracks on the disk by generating the current command signal which is varied in response to a current feedforward signal that defines a head position profile during the seek, varied in response to a position response signal that defines an expected actuator movement response of the head to the current feedforward signal, and varied in response to a current feedback signal. The servo controller measures an open loop response of the actuator to an open loop test current signal, and uses the measured position mode seek performance to vary contributions of the current feedforward signal and the position response signal to the current command signal to improve the position mode seek performance.