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--162 Change 6 2--12 PREPARATION FOR FIRING — CONTINUED 2--12.1 Pre-Firing Emplacement — Continued c. Emplacing Infinity Aiming Reference M1A1/M1A2 Collimator The M1A1 collimator is radioactively illuminated. Check for presence of illumination and damage. If discovered broken, damaged, or defective, follow the procedures on pages b and c. WARNING NOTE • The M1A1/M1A2 collimator is emplaced during the laying operation. Alinement of the M1A1/M1A2 collimator is done after the laying operation is complete. • The M1A1/M1A2 collimator should be emplaced in a concealed position. Placing M1A1/M1A2 collimator between 2400 and 2800 mils will minimize displacement. Emplacement distance away from weapon will vary due to type of terrain encountered, but must be within a minimum of 4.37 yards (4 m) and a maximum of 16.4 yards (15 m). Optimum distance is between 5 and 13 yards (5 and 12 m). M1A1/M1A2 collimator should not be emplaced more than 4.37 yards (4 m) above or below M117/M117A2 panoramic telescope. • M1A1/M1A2 collimator has a self-luminous radioactive light source (see warning above). 1 Under directions from gunner, the M1A1/M1A2 collimator (21) is emplaced by cannoneer no. 3 as follows. (a) Unfasten strap (49) which retains tripod legs (50). (b) Extend tripod legs (50) as necessary. Lock by tightening locking knob (51). (c) Rotate tripod legs (50) to down position and set each tripod leg firmly into ground with one tripod leg pointed toward M117/M117A2 panoramic telescope (36). (d) Release three latches (52) that retain cover (53) and remove cover from tripod. Place cover underneath M1A1/M1A2 collimator (21) with closed end pointing to muzzle brake of weapon. (e) Unfasten strap (54). Loosen elevation adjustment clamping knob (55) and rotate M1A1/M1A2 collimator (21) to a horizontal position. Tighten elevation adjustment clamping knob.