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 489 of 775

TM 9-2350-311-10

3-7 FIRE CONTROL ALINEMENT TESTS AND MEASUREMENTS — CONTINUED

3-7.2

M1A1 Gunner’s Quadrant Tests — Continued

b. End-For-End Test — Continued

14

15

16

17

18

19

20

21

22

23

24

25

26

Bubble (7) should center. If bubble centers, end-for-end testis complete. Record end-for-end correction.

If bubble does not center, go to step 15.

Set index arm (2) at minus 10.

Center bubble (7) with micrometer knob (4).

Add micrometer reading to 10.0.

19.8

Divide step 17 answer by 2. This is your trial correction. An example

2

= 9.9

Place answer on micrometer knob (4).

Position M1A1 gunner’s quadrant (3) with LINE OF FIRE arrow (6) pointing toward muzzle brake.

Depress or elevate cannon tube to center bubble (7).

Reverse direction of M1A1 gunner’s quadrant (3).

Bubble (7) should center. If bubble centers, go to step 24. If bubble does not center, go back to step 15.

Subtract micrometer reading from 10. Since this is a negative correction (step 14) a minus sign must be

placed in front of the correction factor.

Record negative end-for-end correction on case (8).

NOTE

Breech is completely closed when witness marks on breech ring and breechblock aline.

If necessary, open breech and close completely.

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