Installation Instructions for the M1091 M109Al/M115/M110 Howitzers and M107 Guns

TM 9-6920-361-13&P

c. End-for-end test. To perform

the end-for-end test of the gunner's

quadrant, refer to TM 9-1290-200-15

and the operator's manual for the major

caliber weapon.

2-7.

Installation Instructions for the M1091

M109Al/M115/M110 Howitzers and M107 Guns. The

14.5-mm gun barrel is mounted in the breech of the

M109/M109A1 155-mm howitzers, the M107 175-mm

gun and the M110 8-inch howitzer as a subcaliber

device. To mount the gun barrel and boresight the piece

follow steps 1 through 13.

Step 2: Remove the bolt. Install breech boresight disc.

(The breech boresight disc is a fired cartridge case that

has a 1/16-inch hole drilled in the center of the cartridge

base.

Step 1: Remove the obturator group, obturator spring,

and firing mechanism housing assembly (refer to the

operator's manual for the major caliber weapon).

Step 2: Remove adapter nut and washer.

Step 3: Attach cross thread to the muzzle.

Step 4: Sight the tube onto a distant aiming point (1, 500

meters). Aline panoramic telescope sight on the same

distant aiming point using the tangent screws on the

telescope mount or the telescope boresight adjusting

screw

NOTE

When the M115/M117 panoramic

telescope is mounted in the support

it is 1600 mils out of boresight. Since

Step 3: Install the key in the appropriate keyway and

it is impractical to turn the azimuth

secure with a screw: The top keyway is for the

scale 1600 mils using the boresight

M107/M110 weapons, the side keyway is for the M109

adjusting screw, the telescope head

and M109A1 155-mm howitzers. Adapter PN 11578870

will be turned to the distant aiming

has no keyway. Install screw in appropriate screw hole.

point, and then the reset counter will

be set to 3200. Use only the lower

scale for laying and referring.

Change 1 2-15