The information I have indicates that for an AK sighted for and shooting at 100 meters a full turn of the front sight (up or down) will change the POI, 20 cm or 7.8".
The methodology is complicated. The correction factor for an AK set at 100 meters is .0378 (based on the sighting line of 378mm/distance between the front and rear sight). A shot 10cm (4") low would require lowering the front sight 0.0378 times 10 equaling 0.378mm/approx 0.4mm or .015". As the distance at which the rear sight is set increases, the sighting line (distance between the front and rear sight) decreases, decreasing the correction factor and thereby the actual sight correction.
"Many men are able, most aren't willing"