Taller front sight. You need to push the muzzle down so it aims lower and lowers your POI compared to your POA.
In the mean time, can you change how you line up the front and rear site? shift the front site when aiming so it just clears bottom of the groove in the rear site?

Also, I wouldn't expect the POI to shift much (more then a few inches) in 50 yards due to velocity/weight differences between loads.