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 269 of 775
TM 9--2350--311--10
2--171
2--12 PREPARATION FOR FIRING — CONTINUED
2--12.2
Boresighting — Continued
a. Preliminary Procedure — Continued
5
Use M1A1 gunner’s quadrant (5) that has been checked by micrometer test and end-for-end test
(para 3--7.2). Level gun trunnions as follows.
(u) Set index arm (6) and micrometer knob (7) to zero.
(v)
Set M1A1 gunner’s quadrant (5) with end-for-end correction applied on cross-level seats (8) on
breech ring.
(w) Traverse howitzer until bubble (9) centers (test target method only).
6
Set cannon tube at zero elevation (para 3--7.5).
7
Center bubbles in pitch level (10) and cross-level (11) of M145/M145A1 telescope mount (12).
5
6
7
8
9
10
11
12
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