TM-9-2350-311-10 M109 Operator's Manual for M109A2, M109A3, M109A4 and M109A5 Download
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TM 9-2350-311-10 2-12 PREPARATION FOR FIRING — CONTINUED 2-12.3 Standard Angle Method — Continued b. Boresighting Using the Standard Angle Method (Field Situation) — Continued NOTE A parallax shield can be made to prevent eye movement in two ways. One is to use a dust cap with a hole in the center. The second is to use a small opening marked off with strips of tape. 8 Using a parallax shield, turn the M117/M117A2 panoramic telescope (11) azimuth knob (12) to aline the vertical hairline (13) of the M117/M117A2 panoramic telescope on the farthest left edge of the muzzle brake (4). Aline horizontal hairline (14) of the M117/M117A2 panoramic telescope on the top edge of the muzzle brake by turning the M117/M117A2 panoramic telescope elevation knob (15). 9 Note the reading on the M117/M117A2 panoramic telescope (11) azimuth counter (16). If the reading equals the standard angle of deflection, the howitzer is boresighted. If the reading does not equal the standard angle of deflection, go to step 10. 10 Using a screwdriver, depress the boresight detent shaft (17) and adjust the azimuth counter (16) until it displays the standard angle of deflection. Repeat step 8. The weapon is now boresighted. 2-198 Change 2