Rear sight test

Page Title: Rear sight test
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MIL-R-1296F(AR)

4.5.2 Rear sight test.

4.5.2.1 Movement - per-click and backlash tests. The rear

sight shall be adjusted to approximately the middle of both

elevation and windage travel. The elevation knob shall be turned

three (3) clicks clockwise. The height of the aperture disc

shall be recorded. Then the elevation knob shall be turned ten

(10) more clicks clockwise, then ten (10) clicks counter-

clockwise. The actual amount of elevation change of the aperture

disc shall be recorded for each of the twenty clicks.

The nominal movement per click shall be calculated as follows:

CM nom = (SR) (Tangent MOA nom)

Where: CM nom=Nominal Movement per click in inches

= Distance between rear of sight aperture and

rear of front sight aperture of a typical

rifle in inches

MOA nom = nominal sight movement specified in the

operator's manual (in minutes of angle)

The average movement-per-click shall not varY from the

nominal by move than 15 percent of the nominal. The actual sum

of the movement of the first two counterclockwise clicks shall

not vary more than 50 percent from the nominal movement of two

clicks. The difference i height of the disc before and after the

twenty clicks (backlash) shall not exceed one thousandths (.001)

of an inch. The test shall be repeated for windage with the same

acceptance criteria.

4.5.2.2 Free movement test, A four-ounce load shall be

applied to the aperture disc parallel to the elevation screw and

at right angles to the line of sight. The location of the

aperture disc in the plane of the force shall be determined. The

force shall then be applied in the opposite direction and the

location of the disc determined. The difference between the two

locations shall not exceed one-thousandths (.001) of an inch.

The test shall be repeated with the force applied parallel to the

windage screw using the same acceptance criteria.

4.5.3 Safety actuation force test. The rifle shall be

tested using a contractor designed, Government approved measuring

device. The rifle shall be cocked and the safety device shall be

in the fire position. The load shall be gradually applied to the

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