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 Change 3 3–97 3–7 FIRE CONTROL ALINEMENT TESTS AND MEASUREMENTS — CONTINUED 3–7.5 Leveling the Cannon Tube — Continued b. Leveling the Cannon Tube Using the M1A1 Gunner’s Quadrant NOTE • Top surfaces of cannon tube quadrant seat must be free of paint prior to being used for taking readings with M1A1 gunner’s quadrant. • The cannon has quadrant seats on the top muzzle brake end of the cannon tube and on the top of the breech ring. The embedded correction (the difference between muzzle and breech elevation) is measured rather than being stamped on the breech. Breechblocks that have stamped embedded corrections should be disregarded during cannon tube leveling test. 1 Place a tested M1A1 gunner’s quadrant (13) on the top surface of cannon tube quadrant seat (17). Apply only the M1A1 gunner’s quadrant correction, if any, and center the elevation bubble (3) by manually elevating or depressing the cannon tube (2). The cannon tube is now at 0 mils. 17 Top Surface Bottom Surface 13 2 3