M-203, M-79

Grenade Launchers

Sight Adjustment

The LEAF SIGHT is used in conjunction with front sight post of the M16A1 rifle and provides range selection from 50 to 250 meters in 50 meter increments. Turning windage screw clockwise moves sight leaf to left for left wind. Counterclockwise adjusts for right hand wind. One increment equals 1.5 meters at 200 meters range.
The elevation adjustment screw compensates for distance corrections. Raising leaf sight increases range anc lowering leaf sight decreases range. One increment equals 10 meters at 200 meters range. The rim of a used 40mm cartridge can be used to turn the screw.



The QUADRANT SIGHT attaches to the rifle handle/sight and has range from 50 to 400 meters in 25 meter increments. Elevation adjustment: 1 notch - 5 meters at 200 meters. The rear aperture slides in or out for windage correction by depressing retainer. Vertical line denotes center. 1 notch equals 1.5 meters at 200 meter range. Turn front sight post right for less elevation and left for more elevation. Slide the rear aperture in (towards carrying handle)to move strike of projectile right; Slide out (away from carrying handle) to move strike left.

1. FAILURE TO FIRE

Step 1. Check for dirt in firing pin.

Clean firing pin recess.

Step 2. Check for dirt in cartridge Iocator slot.

Clean cartridge Iocator slot.

Step 3. Check for water or oil in firing pin recess.

Point muzzle up and handfunction barrel and firing mechanism.
 

Step 4. Check for broken or improperly assembled parts of firing mechanism.

Step 5. Check for defective cartridge Iocator spring :

a. Using cleaning rod section, push cartridge Iocator toward muzzle, and then release.
b. Cartridge Iocator must move forward and back under spring pressure.

2. FAILURE TO EXTRACT.

Step 1. Check for stuck cartridge case  in barrel.

Remove case by tapping with rifle cleaning rod.

Step 2. Check for broken or missing extractor, spring pin, or spring.

Replace extractor, spring pin,or spring if broken or missing.

3. FAILURE TO LOCK.
 

Check for dirty follower or receiver cavity.

a. Remove back plate and follower
b. Clean and lubricate back plate and follower
c. Clean and lubricate trigger housing

4. FAILURE OF THE LEAF SIGHT ASSEMBLY TO REMAIN AT THE SELECTED RANGE.

Step 1. Check for loose screw  on front folding leaf sight assembly .

Tighten screw.

Step 2. Check for loose screws  on sight leaf base.

Tighten screws.

5. FAILURE OF QUADRANT SIGHT ASSEMBLY TO STAY IN SELECTED POSITION.

Check quadrant sight assembly for damage (broken quadrant locator teeth. bent or damaged parts).