2.4.4. To zero the rifle with the optical sight attach it to the rifle and put the cheek plate on the butt. Rotate the knobs to set the sight angle knob at division 3 and deflection correction knob at 0. Perform the test-firing with the aid of the optical sight, the conditions being the same as for test-firing of the rifle with the aid of the open sight, but the check point in this case is marked at a height of 14 cm from the point of aim.
If, as a result of the test-firing, all four hits are arranged in a circle, 8 cm in diameter, but the mean point of impact deviates from the check point by more than 3 cm, determine the deviation of the MPI and introduce the appropriate corrections into the settings of the nuts on knobs of the sight angles and deflection corrections.
Displacement of the nuts by one division relative to the scales on the bands of the knobs in firing at 100-m range will change the position of MPI by 5 cm. To introduce corrections release screws on the knob ends by 1 1 1/2 turns and while rotating the sight angle nut and the deflection correction nut, manually, displace them by a necessary amount and tighten the screws.
After the corrections have been introduced in the knob setting, repeat the test-firing. If, as a result of the repeated test-firing, all the four hits are arranged in a circle, dia. 8 cm, the MPI has matched with the check point or deviated from it to either side by no more than 3 cm, the rifle is considered zeroed.