TM-9-2350-311-10

HOWITZER, MEDIUM, SELF-PROPELLED, 155MM; M109A2, M109A3, M109A4 AND M109A5

TECHNICAL MANUAL; OPERATOR’S MANUAL

NOVEMBER 1994

TM-9-2350-311-10 - Page 272 of 775

TM 9-2350-311-10

2–12

PREPARATION FOR FIRING — CONTINUED

2-12.2

Boresighting — Continued

b.

Test Target Method — Continued

5

6

7

8

NOTE

·

Keep the panoramic telescope ballistic cover perpendicular to line of sight. After alining the

reticles, panoramic telescope ballistic cover may be rotated away from perpendicular and

then returned to it. If reticles are within ± 0.5 mil tolerance correct positioning has been

established. If reticles are separated by more than ± 0.5 mil displacement, panoramic

telescope ballistic cover needs to be moved a bit more toward perpendicular.

·

When viewing through M117/M117A2 panoramic telescope, parallax may occur if

panoramic telescope ballistic cover is rotated. Panoramic telescope ballistic cover must be

kept perpendicular to line of sight to keep parallax at a minimum.

Adjust azimuth knob (16) and elevation knob (17) on M117/M117A2 panoramic telescope (18) to lay

reticle precisely on left aiming diagram (15) on test target (13).

Check that muzzle crosshairs (3) are still centered on aiming diagram (15).

Check cross-level (11) and pitch level (10) to be sure M145/M145A1 telescope mount (12) is level.

Azimuth counter (19) should read 3200 mils. If it does not, remove cover (20) from boresight detent shaft

(21). Insert small screwdriver and depress boresight detent shaft. Turn boresight detent shaft until 3200

mils appears in azimuth counter. Recheck sight picture to be sure M117/M117A2 panoramic telescope

(18) is still in boresight.

2-174