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This chapter identifies some of the problems that can cause the M203 grenade launcher to perform incorrectly. It also explains how to identify unserviceable parts and how to destroy the weapon when authorized to do so.


A malfunction occurs when a mechanical failure prevents the weapon from firing properly. Neither defective ammunition nor improper operation of the weapon by the firer is a malfunction. The weapon should be cleaned, lubricated, and retried. If it still fails to function, it should be turned in to the unit armorer. Table 4-1 shows probable causes and corrective action for each type of malfunction.


Probable Cause

Corrective Action

Failure to cock

Broken sear

Notify unit maintenance

Improper assembly of cocking lever

Loose, broken, or missing cocking lever spring pin

Failure to lock

Excess plastic on breech end of barrel assembly

Table 4-1. Malfunctions.


A stoppage is an unintentional interruption in the cycle of operation or functioning that may be cleared by immediate action. A stoppage is classified by its relationship to the cycle of functioning. Table 4-2 shows the types of stoppages.


Probable Cause

Corrective Action

Failure to fire

Safety on

Place in fire position

Empty chamber


Faulty ammunition


Water or excess lubricant
in firing pin well

Hand cycle weapon several times, to include pulling the trigger

Worn or broken firing pin

Notify unit maintenance

Dirt or residue in firing pin recess


Blurred sear or firing pin

Notify unit maintenance

Dirty firing pin well opening

Weak or broken firing pin spring

Failure to extract

Defective extractor on spring or spring pin

Ruptured cartridge case

Remove from barrel

Failure to eject

Worn, broken, or missing
ejector spring or retainer

Notify unit maintenance

Failure to chamber

Faulty ammunition


Dirty chamber

Clean bore and chamber

Safety fails to stay in position

Missing spring pin or
broken or worn safety

Notify unit maintenance

Table 4-2. Stoppages.


Immediate action refers to anything a soldier does to reduce a stoppage without taking time to look for the cause. Immediate action should be taken in the event of either a hangfire or misfire. Either can be caused by an ammunition defect or by a faulty firing mechanism. Any failure to fire must be considered a hangfire until that possibility is eliminated.

  • A hangfire is a delay in the functioning of the round's propelling charge explosive train at the time of firing. The length of this delay is unpredictable, but in most cases, it ranges between a split second and 30 seconds. Such a delay in the functioning of the round could result from the presence of excess oil or grease, grit, sand, frost, or ice.
  • A misfire is a complete failure of the weapon to fire. A misfire in itself is not dangerous, but because it cannot be immediately distinguished from a hangfire, it must be considered to be a hangfire until proven otherwise.

Because a stoppage may be caused by a hangfire, the following precautions must be observed until the round has been removed from the weapon and the cause of the failure determined:

a.   Keep the M203 pointed downrange or at the target and keep everyone clear of its muzzle. If the stoppage occurs during training, shout MISFIRE and clear the area of any soldiers not needed for the operation.

b.   Wait 30 seconds from the time of the failure before opening the barrel assembly to perform the unloading procedure.

c.   After removing the round from the receiver, determine whether the round or the firing mechanism is defective. Examine the primer to see if it is dented. If the primer is dented, separate the round from other ammunition until it can be disposed of properly. However, if the primer is not dented, the firing mechanism is at fault. Once the cause of the failure to fire has been corrected, the round may be reloaded and fired.


If you are unloading a weapon that has not been fired, avoid detonation either by catching the ejected round or by holding the weapon close to the ground to reduce the distance the round can fall.


Remedial action is any action taken by the gunner to restore his weapon to operational condition. Take remedial action only if immediate action does not remedy the problem.


Destruction of any military weapon is authorized only as a last resort to prevent the enemy from capturing or using it. This paragraph discusses planning for destruction, priorities and methods of destruction, and degree of damage. In combat situations, the commander has the authority to destroy weapons, but he must report doing so through channels.

a.   Planning. SOPs for all units should contain a plan for destroying equipment. Having such a plan ensures that the damage is effective enough to deny use of the equipment to the enemy. The plan must be flexible enough in its designation of time, equipment, and personnel to meet any situation.

b.   Priorities of Destruction. When lack of time prevents them from completely destroying equipment, soldiers must destroy the same essential parts on all like equipment. The order in which the parts should be destroyed (priority of destruction) is as follows:

(1)   Bolt assembly (M16) and breech mechanism (M203).

(2)   Barrels (both M16 and M203).

(3)   Sights or sighting equipment (including nightsight).

(4)   Optics mount.

c.   Methods of Destruction. Equipment may be destroyed by any of several methods. The commander must use his imagination and resourcefulness to select the best method of destruction based on the facilities available. Time is usually critical. The methods of destruction are as follows:

(1)   Mechanical. Use an axe, pick, sledgehammer, crowbar, or other heavy implement.

(2)   Burning. Use gasoline, oil, incendiary grenades, other flammables, or a welding or cutting torch.

(3)   Demolition. Use suitable explosives or ammunition or, as a last resort, hand grenades.

(4)   Disposal. Bury essential parts, dump them in streams, or scatter them so widely that recovering them would be impossible.

d.   Degree of Damage. The method of destruction used must damage equipment and essential spare parts to the extent that they cannot be restored to usable condition in the combat zone, either by repair or by cannibalization.

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