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--188 Change 6 2--12 PREPARATION FOR FIRING — CONTINUED 2--12.2 Boresighting — Continued f. Comparison Test of the M140/M140A1 Alinement Device — Continued NOTE Correct azimuth reading is 3200 mils. 4 To determine which M140/M140A1 alinement device (27) is unserviceable, obtain a third M140/M140A1 alinement device and check boresight of weapon again. 5 Without changing azimuth reading, install each of the other two M140/M140A1 alinement devices (27). The M140/M140A1 alinement device on which reticles will not aline with M117/M117A2 panoramic telescope (18) reticle is defective. Turn in defective M140/M140A1 alinement device to unit maintenance for repair.