Installation Instructions for the M198 Howitzer (cont)

TM 9-6920-361-13&P

Step 10:

Close the breech, remove the bolt by pulling

down on the locking cap and pulling bolt to the rear. To

boresight the 14.5-mm device:

1. Tighten both elevating adjusting screws

against the barrel.

2. Place the breech boresight disc in the

cartridge chamber.

3. Sighting through the breech boresight disc,

aline the horizontal boresight string of the 14.5-mm

barrel with the horizontal boresight string of the primary

weapon by adjusting the elevating adjusting screws (the

rear screw lowers the barrel, the front screw raises the

barrel).

4. Tighten the four adapter cap screws.

Verify the alinement of the muzzle

Step 8: Place the gun barrel in the adapter and engage

horizontal boresight strings.

Remove the muzzle

the barrel trunnions with the adapter slots.

boresight strings from the primary weapon.

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

1, 500 meters from the weapon.

7. Sighting through the breech boresight disc,

aline the 14.5-mm barrel on the DAP.

8. Refer the panoramic sight on the DAP. The

reading should be zero. If it does not read zero, set to

zero. Then adjust the sight on the DAP using the target

adjusting screws.

9. Open breech and remove boresight strings

from muzzle of subcaliber device.

10. Close breech, remove boresight disc and

install bolt.

Step 9: Lock the barrel into position by securing adapter

cap to the body. Do not tighten the four screws yet.

CAUTION

Use caution if opening breech with

barrel assembly installed to prevent

barrel assembly from striking top

carriage.

Step 11:

Turn the safety ring to the :fire: position.

Place the lanyard ring over the rear of the breech,

matching the openings of breech and the lanyard ring.

Change 1 2-22.2