C 10, TM 9-2350-230-12
TABLE 2-10. OPERATION OF INDIRECT FIRE CONTROL INSTRUMENTS
STEP
PROCEDURE
FIG/ITEM
1
Traverse turret and elevate or depress 152MM gun-launcher until
gunner's periscope (XM44 Series) or telescope (M1i9 or M127)
conventional reticle is exactly on reference point.
2
Depress slightly and rotate resetter knob of azimuth indicator until
micrometer pointer coincides with azimuth pointer. Depress resetter
knob further and rotate both pointers to zero.
3
To determine the deflection to a given target, traverse the turret until
the aiming cross of the gunner's periscope reticle is properly aligned
on the target. Read directly from the azimuth indicator the sum of the
micrometer and azimuth pointers.
4
To make small deflection corrections, rotate gunner's aid dial until
zero graduation is opposite micrometer pointer. Use the micrometer
pointer in conjunction with the gunner's aid (dial) to make a right or
left shift of 50 mils or less in deflection.
5
Rotate micrometer elevation knob of M13A1C elevation quadrant until
sum of elevation scale and micrometer scale readings equal required
elevation angle. Elevate or depress gun-launcher until bubble in level
vial is centered. Gun is now layed in elevation.
NOTE. 1. If possible, the vehicle should be positioned on level
ground.
2. Either M1SAIC elevation quadrant or M1A1 gunner's
quadrant may be used to lay gun in elevation. If M1A1 quadrant is
used, note any deviation between centerline of weapon and quadrant
seat (stamped above quadrant seat, fig. 2-28). If deviation exists,
compensate by presetting quadrant.
6
Disengage index plunger from notches in frame of M1A1 gunner's
quadrant by pressing plunger into index arm. Raise index arm and
set index plate to nearest graduation on elevation scale below required
elevation angle. Rotate micrometer knob to fine reading.
NOTE. If required elevation angle is 327 mils, set index plate at 32C
mils, and turn micrometer knob until scale indicates 7 mils: quadrant
is now set at 327 mils.
7
Place shoes of MlA1 quadrant on quadrant seat of 152MM gun-launcher
mount with inscribed arrow on quadrant pointing toward muzzle end
of gun-launcher. Elevate or depress gun-launcher until bubble in
level vial is centered. Gun-launcher is now layed in elevation.
NOTE. Before using, wipe shoes of gunner's M1A1 quadrant and
quadrant seat to insure accuracy.
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