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 a. Determining the Standard Angle — Continued 7 Boresight using the test target method (para 2-12.2). 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 way is to use a small opening marked off with strips of tape. • Final movement of the azimuth knob when making any setting should be in a clockwise direction. 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 the horizontal hairline (14) of the M117/M117A2 panoramic telescope on the top edge of the muzzle brake by turning the elevation knob (15). 9 Record the reading from the Ml 17/M117A2 panoramic telescope (11) azimuth counter (16) to the nearest 1/4 mil. This is the standard angle of deflection for this M145/M145A1 telescope mount (6), Ml 17/M117A2 panoramic telescope, and howitzer. Change 2 2-195