 This is the machine gun 7.62 millimeter M60. It is an automatic weapon. It is gas operated, air cooled, belt fed and weighs 23 pounds with its organic bipod. This gun has a maximum effective range of 1100 meters and a muzzle velocity of 2,750 feet per second. It is fed from a disintegrating belt. The M60's cyclic rate of fire is approximately 550 rounds per minute. Its sustained rate of fire is 100 rounds per minute and at the rapid rate 200 rounds per minute. The caliber of the gun and the 7.62 millimeter ammunition conform in all respects to standards adopted by the North Atlantic Treaty Organization. The gun fires three types of ammunition, ball, tracer and armor piercing. It is linked for field use in a ratio of four ball, one tracer. The gun is normally fired from a bipod as here or a tripod mount but it can be fired from the hip on the move and in close quarters. The bipod provided for the machine gun M60 is held in place by the flash suppressor. The bipod legs are unfolded by pulling them rearward and lowering them. They automatically lock. The bipod legs are extended by pulling down on the bipod feet. Loading of the machine gun is accomplished with the cover down and the bolt forward. The assistant gunner places the first round of the ammunition belt over the belt holding pole. The gunner then pulls the cocking lever handle to the rear, fully loading the gun. The cocking lever handle is moved forward and the gun is ready to fire. The gun is aimed by means of front and rear sights. The front sight is of a fixed blade type. The rear sight is of a folding leaf type and is capable of quick adjustment. Range settings are made by moving the rear sight slide up or down. Windage adjustments when zeroing are made by turning the traverse knob at the lower left hand side of the rear sight. When the gun is zeroed, you are ready to fire. Put the safety on fire. Aim and pull the trigger. The gun will continue firing as long as the trigger is held back or until the ammunition belt is exhausted. The M60 is fully automatic. Short bursts can be fired if the trigger is released after each burst. When the trigger is released, if the ammunition belt is not exhausted, the bolt will remain to the rear. With the bolt to the rear, the gun is cocked and ready to be fired. To unload the gun, the gunner opens the feed cover and the assistant gunner removes the belt from the feedway. Close the feed cover and let the bolt move forward by pulling the trigger. If all of the ammunition has been fired, the bolt will be forward, the chamber will be empty. Before reloading, the gunner raises the cover, knocks the remaining link from the feed plate, pulls the bolt to the rear, closes the cover and allows the bolt to go forward. He then reloads. The tripod mount for the M60 allows control, traverse and search by using the traversing and elevating hand wheels. Each gun has a spare barrel group. The barrel group should be changed after firing the sustained rate of fire for 10 minutes or the rapid rate of fire for 3 minutes. This will help prolong the life and maintain the accuracy of the barrel. To change the barrel, the gunner raises the barrel locking lever. The assistant gunner withdraws the barrel by grasping the bipod legs and inserts the new barrel into the receiver. Now the gunner lowers the barrel locking lever. The barrel change is completed. Barrels are changed in a matter of seconds. Frequent changes avoid overheating of the barrel and increase the effective sustained fire capability of the gun. Saving your barrel may save your life. The machine gun breaks down into six groups for general disassembly in the field. Number one, the buttstock group. Number two, the buffer group, consisting of the buffer and the buffer locking plate. Number three, the operating group, which includes the operating rod, the bolt, the operating rod drive spring, and the operating rod drive spring guide. Number four, the trigger housing group, consisting of the trigger housing, the spring lock, and the front trigger housing holding pin. Number five is the barrel group, which includes the barrel socket, the barrel, the gas cylinder, the bipod, the flash suppressor, and the front sight. Number six is the receiver group. With the barrel locking lever, the rear sight, the feed cover, and the feed plate. In general, many parts of the groups have been designed to be replaced as complete assemblies. This should make repairs of individual parts by using units almost unnecessary. We shall now see how the M60 functions. Each time a cartridge is fired, the parts of the machine gun move in a given sequence and perform definite jobs. This is known as the cycle of functioning. For instructional purposes, this cycle will be divided into eight steps. The first step is feeding, which is positioning the cartridge ready for chambering. The second step is chambering, the function of seating the round in the chamber. The third step is locking the bolt inside the barrel, thus holding the cartridge seated in the chamber, so that gas pressure will be maintained in the barrel to propel the bullet. The fourth step is firing, ignition of the primer of the cartridge in the chamber. Step five is unlocking the bolt from the barrel. Step six is extraction of the empty cartridge case from the chamber. In step seven, the empty cartridge case is ejected from the gun, and step eight is cocking. These eight functions happen one after another and so rapidly as to be almost simultaneous. The cyclic rate of fire of the M60 machine gun is approximately 550 rounds per minute. This means that a bullet leaves the muzzle each tenth of a second while the gun is being fired. With the help of an oversized model, we'll be able to see exactly what goes on inside the gun. In this film, the functions of the gun will be demonstrated step by step. But remember, in actuality, these occur very fast and overlap each other. This is the belt holding ball on the feed plate. Feeding begins when the first round is positioned over the ball. The purpose of the ball is to prevent the rounds from falling out of the feedway. Before you see the movements of the parts in feeding, note the location of the actuating cam roller on top of the bolt. As the bolt moves, the roller moves. As the bolt is moved rearward, the actuating cam roller moving in the feed cam forces the feed cam to move to the left, and the feed cam lever and belt feed pawls to move to the right. As the feed cam lever and the feed pawls move to the right, they pull the first round with them and position it in the feed plate groove. The first round is now in front of the bolt and directly behind the chambering ramp. The bolt is carried forward by the operating rod. The actuating cam roller now moves the feed cam to the right. This moves the belt feed pawls to the left. Let's repeat the action. The feed pawls slide over the second round in the belt and then to the left of the round. The feed pawls will stay here until the bolt moves to the rear. This completes the first step, feeding. Chambering begins with a round in the feed plate groove and the bolt and operating rod to the rear. When the round is in the feed plate groove, the front cartridge guide and the rear cartridge guide place downward pressure on the round to hold it in position. These guides are under spring tension. The rear end of the front cartridge guide will block the forward movement of the belt link. To chamber a round, the trigger must be pulled. First though, let's see how the trigger and sear operate. When the safety is placed in the safe position and the trigger pulled, it will prevent the rear of the sear from pivoting downward. With the safety in the fire position, the rear of the sear pivots downward when the trigger is pulled, releasing the operating rod and allowing the operating rod drive spring to expand. When the trigger housing group is properly attached to the gun and the trigger pulled, the sear disengages from the sear notch. The operating rod driven by its expanding spring starts forward. The bolt travels forward also and we shall now see how the cartridge is stripped from the belt. In the M60, the round is stripped from the belt link in a single forward action by the upper locking lug striking the rim of the cartridge moving it forward. The link is firmly held by the front and rear cartridge guides and cannot move forward with the cartridge. The nose of the round is guided down into the chamber by the chambering ramps. Let us repeat the action. The ramps guide the round downward toward the chamber. The bolt locking lugs now contact the curved surfaces of the barrel socket. The bolt starts to rotate clockwise. The extractor engages the rim of the cartridge. Chambering is completed. Locking began with chambering. As the parts move forward, the operating rod yoke engaged in the bolt camming slot aids in rotating the bolt in a clockwise direction. The locking lugs engage the locking recesses of the barrel socket. Locking is completed. The next step is firing. The forward movement of the operating rod carries the firing pin forward. The firing pin strikes the primer of the cartridge and ignites the round. Firing has been accomplished. The expanding gasses propel the bullet through the barrel. When the bullet passes the gas cylinder port, gas moves from the barrel through the gas port into the gas cylinder. Here it enters the piston through the ports in the collecting ring. The gas expands and forces the piston to the rear. The piston strikes the operating rod and begins the rearward movements of the operating parts. The expanding gas moves through the front gas cylinder nut in the gas cylinder extension. Excess gas escapes at the bleeder hole. The remaining gas escapes at the gas escape ports at the rear of the cylinder. Unlocking begins with the rearward movement of the operating rod. As the operating rod travels rearward, there is a slight delay before the bolt is unlocked from the barrel socket. Here is why. The operating rod has a short period of free travel. As the camming yoke passes through the straight portion of the bolt camming slot, when the camming yoke reaches the curved portion of the bolt camming slot, it forces the bolt to rotate in a counter-clockwise direction. The bolt locking lugs and the locking recesses of the barrel socket are at such an angle that counter-clockwise rotation of the bolt during unlocking permits a slight rearward movement. The now tightly seated cartridge case is loosened in the chamber. This prevents the extractor from tearing through or slipping over the head of the cartridge case. The operating rod overcomes the resistance of the bolt. Unlocking is completed. Extracting and ejecting now begin. The empty cartridge case gripped by the extractor is drawn from the chamber. In this view, you see the ejector on the other side of the bolt. It was compressed during chambering and exerts forward pressure on the rim of the cartridge. When the empty case reaches the ejection port in the right side of the receiver, the ejector spins the case from the gun. Ejection is completed. The next round pushes out the link. The firing pin spring is compressed and cocking is accomplished. The operating rod drive spring is compressed. The operating rod drive spring guide is in contact with the buffer plunger. The moving operating rod compresses the spring against the head of the operating rod drive spring guide. The buffer plunger forces the buffer pads rearward against the buffer return springs. The buffer pads expand against the buffer tube body. The pads and springs absorb the rearward energy and the cycle has been completed. However, the energy stored in the compressed operating rod drive spring is prepared to carry the operating rod forward and start the entire cycle all over again. The M60 will fire automatically as long as the trigger is held to the rear. When the trigger is released, the rear end of the sear pivots upward and engages the sear notch in the operating rod and fire ceases. The gun has been automatically cocked. The bolt has remained to the rear and is ready to begin the forward movement of the cycle. A round is ready to be chambered. The machine gun 7.62 millimeter M60 is easy to load. It is easy to unload. It is a gas operated air cooled and belt fed machine gun that performs its eight necessary functions in very nearly simultaneous actions. Ammunition for the weapon is available in several categories. The M60 is a versatile tracer, armor piercing and for field use linked four ball to one tracer. The M60 is a versatile machine gun. It can be fired from a lightweight tripod mount. Barrels are changed in a matter of seconds. It can also be fired from its organic bipod. Its cyclic rate of fire of approximately 550 rounds per minute combined with its versatility provides a potent automatic weapon delivering a close continuous volume of fire.