TM-9-2350-311-10

HOWITZER, MEDIUM, SELF-PROPELLED, 155MM; M109A2, M109A3, M109A4 AND M109A5

TECHNICAL MANUAL; OPERATOR’S MANUAL

NOVEMBER 1994

TM-9-2350-311-10 - Page 284 of 775

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).