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--172 Change 6 2--12 PREPARATION FOR FIRING — CONTINUED 2--12.2 Boresighting — Continued b. Test Target Method WARNING The test target method of boresighting must be used to check M140/M140A1 alinement device. Failure of M140/M140A1 alinement device reticle to aline with reticles of M117/M117A2 panoramic telescope and M118A2/M118A3 elbow telescope could result in projectiles landing outside target area. Injury or death of friendly forces can result from firing with misalined fire control equipment. 1 Perform all preliminary procedures (para 2--12.2a.). 2 Prepare test target (13) as follows: (a) Fasten test target (13) to a stand (14) for stability. (b) Prior to boresighting in dark, drill a 1/16 inch (1.59 mm) hole through center of each aiming diagram (15). Cover holes with a piece of cloth. At night, hold a flashlight to the boresight, against the cloth. NOTE Measurements do not appear on test target. They are shown in case it is necessary to make a test target. 3 Locate test target (13) 55 yards (50 m) in front of howitzer. 4 Without moving cannon tube, aline center of aiming diagram (15) with muzzle crosshairs (3).