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--186 Change 6 2--12 PREPARATION FOR FIRING — CONTINUED 2--12.2 Boresighting — Continued e. Checking Boresight of the M118A2/M118A3 Elbow Telescope Using the M140/M140A1 Alinement Device — Continued NOTE If alinement of M140/M140A1 alinement device and M118A2/M118A3 elbow telescope is not obtained, a comparison test must be performed (para 2--12.2f.). 4 If after verifying accuracy of the M140/M140A1 alinement device (27), alinement is not obtained, boresighting must be conducted using test target method (para 2--12.2b.) or distant aiming point method (para 2--12.2g.) CAUTION In order to prevent damage to M118A2/M118A3 elbow telescope, stow against upper stop when not in use. Do not use as a handhold under any circumstances. f. Comparison Test of the M140/M140A1 Alinement Device WARNING The M140 alinement device is radioactively illuminated. Check for loss of luminescence, breakage, damage, or defects. If present, follow the procedures on pages b and c. NOTE • Comparison test of M140/M140A1 alinement device is performed to identify any device that has been bent or damaged due to accident or mishandling. Reference to azimuth counters pertains to M117/M117A2 panoramic telescope only. • 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. 1 Check boresight using M140/M140A1 alinement device (27).