Installation Instructions for the M102 Howitzer (cont)

TM 9-6920-361-13&P

Step 4: Attach fine thread across the four witness marks

Step 7: Boresight the 14.5-mm gun in the following

on the end of the tube by using a rubber band. Also

sequence:

place boresight strings on the muzzle of the howitzer

1. Remove the bolt and install the breech

boresight disc

2. Sight through the breech boresight disc and

align the horizontal boresight string of the gun with the

horizontal cross-hair string on the howitzer To raise the

barrel. tighten the front elevating adjusting screw To

lower the barrel, loosen the front screw and tighten the

rear screws

3. When the horizontal crosshairs are in

alinement and the two elevating screws are tight, tighten

the four head cap socket screws.

4. Remove the howitzer boresight strings.

5. Select a distant aiming point (DAP) at least

1, 500 meters from the weapon. Sighting thru the breech

boresight disc aline the 14.5-mm barrel on the DAP.

Step 5: Place the gun barrel in the adapter and engage

6. Refer the panoramic sight to the distant

the barrel trunnions with the adapter slots.

aiming point. The reading should be 3200 mils. If the

reading is not 3200, adjust it to 3200 mils.

7. Remove boresight disc and install breech-

bolt.

Step 8: Turn the safety ring to the "tire" position. Place

Step 6: Lock the barrel into position by securing the

the lanyard ring over the rear of the breech, matching

adapter cap to the body Do not tighten the four screws

the openings of breech and the lanyard ring.

yet.

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