The M60 machine gun is loaded, fired, unloaded, and cleared in the OPEN-BOLT position. The safety must be placed in the F (Fire) position before the bolt can be pulled to the rear.

To load the machine gun, check to make sure the safety is in the F position. Using the cocking handle, pull the bolt to the rear. When the bolt is held to the rear by the sear, return the cocking handle to the forward position and place the safety in the S (Safe) position. Raise the cover to ensure that the feed tray, receiver, and the chamber are clear. Place the first round of the belt in the feed tray groove and close the cover, ensuring that the round remains in the feed tray groove.

To unload the machine gun, pull the bolt to the rear, place the safety in the S position, and return the cocking handle to the forward position. Raise the cover and remove any ammunition or links from the feed tray. To clear the machine gun, pull the cocking handle to the rear, place the safety in the S position, and push the cocking handle forward. Then raise the cover and inspect the chamber; if it is clear, close the cover and place the safety in the F position; then pull the trigger. After the bolt has gone forward, place the safety in the S position.

FUNCTIONING

By having a basic knowledge of how the machine gun functions, you should be able to recognize and correct stoppages that occur during firing.

The machine gun is designed to function automatically as long as ammunition is fed into the chamber and the trigger is held to the rear. Each time a round is fired, the parts of the machine gun function in a certain sequence. The sequence of operation is known as the cycle of functioning.

The cycle of functioning is divided into eight basic steps that are listed below in the order they occur; however, more than one step may occur at the same time.

FEEDING-A round is positioned into the feed tray groove.

CHAMBERING-A round is stripped from the belt and placed in the chamber.

LOCKING-The bolt is locked inside the barrel socket.

FIRING-The firing pin strikes and detonates the primer of the cartridge.

UNLOCKING-The bolt is unlocked from the barrel socket.

EXTRACTING-The empty case is pulled from the chamber.

EJECTING-The empty cartridge case is thrown from the receiver.

COCKING-The sear engages the sear notch.

MALFUNCTIONS

A malfunction is a failure of the gun to function satisfactorily. Defective ammunition or improper operation of the gun by either you or one of your crew members is not considered a malfunction of the gun. Two of the more common malfunctions of the M60 machine gun are sluggish operation and a runaway gun. Sluggish operation of the gun is usually caused by excessive dirt or carbon, lack of proper lubrication, burred parts, or excessive loss of gas. Clean and lubricate the gun; inspect for burred parts and have them replaced as necessary by the armorer. Excessive loss of gas is usually caused by a loose or missing gas-port plug. The best method of stopping a runaway gun depends on many factors. Some of these factors are the amount of ammunition remaining in the belt, how the gun is mounted, and whether an assistant gunner is present. For example, in assault firing with the bandoleer attached to the gun, you will continue to move forward, keeping the gun on target until the ammunition is expended. In other types of firing, the primary consideration is keeping the gun on target; however, either you or the assistant gunner may be able to stop the gun by twisting or breaking the belt to stop the feeding. When you have ceased firing the gun, field-strip it and check the sear and sear notch for excessive wear. Check the gas system to ensure that the gas-port plug, gas-cylinder extension, and gas-cylinder nut are tight. Clean the operating rod tube. Replace parts as necessary.

STOPPAGES

A stoppage is any interruption in the cycle of functioning caused by a faulty action of the gun or ammunition. Stoppages are classified by the relationship to the cycle of functioning. Table 13-1 shows the types of stoppages, their causes, and the corrective action to be taken.