Zeroing of rifle and procedure of optical sight operation

Spec Ops Shooting

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2.4.1. The sniper rifle being in the service of a subunit should be zeroed. The necessity of rifle zeroing is determined by test firing.

Rifles are subjected to test firing:

a) on reception of the rifle by the subunit;

b) after the rifle parts repair or replacement, which may affect the rifle fire accuracy;

c) in case of excessive deviation of the mean point of impact (MPI), or bullet dispersion, which does not meet the accuracy requirements. Under combat conditions the rifle accuracy should be tested periodically whenever the situation permits.

2.4.2. The sniper rifle is test-fired by four shots, aiming thoroughly and uniformly with the aid of the open sight. Fire is conducted at the black rectangle, 20 cm wide and 30 cm high, secured on a white board, 1 m high and 0.5 m wide. The point of aim is the middle of the black rectangle bottom edge. During firing when the open sight is used the normal position of the MPI is marked with chalk or a colored pencil by the plumb line, 16 cm above the point of aim. This point serves as the check point (CP).

The range is 100 m; the sight is set at 3. Firing is conducted from the prone position with support. To test-fire and zero a rifle, use should be made of cartridges with ordinary bullets having a steel core. Fire is conducted with knife bayonet removed. Upon firing the shots, examine the target and arrangement of hits; determine accuracy of fire and position of the MPI. The sniper rifle fire accuracy is considered normal, if all the four hits are arranged within the circle, 8 mm in diameter.

If the shot group does not meet the requirements, test firing is repeated.

If the second test results are unsatisfactory, the sniper rifle should be sent to the repair shop.

If the shot group is found normal, determine the MPI and its position relative to the check point.

Determination of the mean point of impact is shown in Fig. 12. The sniper rifle fire accuracy is considered normal, if the mean point of impact coincides with the check point or deviates from it in any direction by no more than 5 cm.

2.4.3. If during test-firing the MPI deviates by more than 5 cm from the CP in any direction, the position of the front sight (as to its height) or that of its body (as to side position) should be changed accordingly. If the mean point of impact is below the check point, the front sight should be screwed in, if it is above the check point, the front sight should be screwed out.

If the MPI is to the left of the CP, the front sight body should be shifted to the left, if to the right, shift the body to the right. The front sight body displacement by 1 mm to the side and one complete revolution of the front sight (when screwed in or out) will change the position of the mean point of impact by 16 cm when fire is delivered at a range of 100 m.

Fig. 12. Determination of mean point of impact (MPI):

1 - by consequent division of lines; 2 - with symmetrical arrangement of hits. CTn means MPI

Fig. 12. Determination of mean point of impact (MPI):

1 - by consequent division of lines; 2 - with symmetrical arrangement of hits. CTn means MPI

Repeat test-firing to make sure that the above displacement of the front sight and its body is properly done.

After the sniper rifle has been zeroed, remove the old notch and make a new notch on the front-sight body.

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 1s1 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.

After zeroing the rifle, record the position of the MPI in the Service Log.

2.4.5. To detect the range up to the target proceed as follows:

Match the target image with the range-finding scale of the reticle so that the target base is on the horizontal line of the range-finding scale, and the target top point touches the upper (dotted) line of the scale without clearance.

Take off the range-finding scale readings in the point of touching the target.

A digit which happens to be in the point of touching determines the distance up to the target (in Fig. 13 the distance up to the target is 400 m).

2.4.6. To deliver firing at night or in twilight turn the micro-tumbler lever to the position "BKJi" (ON).

Sight angles and deflection correction angles are set in this case by counting clicks of the retainer from zero position. Bear in mind that the fixation of the sight angle knob is performed from "0" to "3" every whole division, i.e. every 100 m and further on till setting 10 every half-division i.e. every 50 m. The fixation of the knob of deflection corrections is effected every half division, i.e. every 000.5.

2.4.7. When working with the illuminating system it is necessary to store the set body with the section 2 RC-63 in a warm place (in the pocket of a field shirt or a sniper's overcoat.

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