This is a preliminary version of a not yet published article. As always, comments welcomed.
John
The U.S. M60 machine gun
During World War II United States armed forces found themselves facing an incredibly versatile and effective machine gun fielded by Germany. This was the MG42, which with its very rapid rate of fire earned the nickname “buzzsaw” on the battlefields of Europe. While we had some fine machine guns, none had the rate of fire, portability, and ease of maintenance exhibited by that Teutonic nightmare.
Shortly after WWII the U.S. Army began experimenting with new machine gun designs. They used the MG42 and the FG42 (an even lighter selective fire machine gun designed for paratroopers in Germany) as examples of more modern technology. Attempts to convert these 8mm guns into similar .30-06-chambered U.S. machine guns by the Saginaw Steering Gear division of General Motors were largely unsuccessful. However, the objective remained to ultimately find a single replacement for the M1917, M1919A4 and M1919A6 machine guns then in use as well as the Browning Automatic rifle. These efforts continued.
What evolved in the 1952-1957 period was an interesting combination of newer concepts such as stamped sheet metal components and a belt feed mechanism using a single pawl similar to that used in the MG42. Also developed for evaluation was a quick-release barrel changeout system. A pistol grip enabled hand-held operation when necessary. A semi-“bullpup” placement of the operating rod and buffer in the shoulder stock was used, much like the FG42. This feature allowed a shorter overall length. The gas-powered operating rod turned a rotating bolt similarly to the FG42 and the earlier American-designed Lewis machine gun. The gas operation utilized the “gas expansion and cutoff” principle that was also employed in the M14 rifle. It was relatively simple and easier to clean.
These experimental designs all fired from an open bolt to aid in better barrel cooling. It was decided that with a quick-change barrel, the barrel would be air-cooled rather than using an obsolete water-cooling jacket. Like the M14 rifle, the new machine gun would be chambered for the 7.62x51mm NATO round which was shorter than the 30-06 round that preceded it. It would have a cyclic rate of fire of approximately 500 to 650 rounds per minute and be fed from a 100 to 250-round disintegrating metallic split-link belt. Overall, the gun would be designed to enable mass production, unlike earlier U.S. machine guns that used many parts that required extensive and expensive machining.
At the time of the M60’s development, there were competing designs such as the Belgian FN MAG and the German Rheinmetall MG3. These were evaluated, but a U.S. design was preferred to avoid the extra expense of foreign entanglements. The final experimental version was designated as the T161E3.
The M60 machine gun was formally adopted as standard in January1957, replacing previous machine guns and the M1918A2 BAR. It was first issued to units in 1959. In my Army unit in that time period, we did not acquire them until 1961. I personally showcased one of the new machine guns to interested civilians during a weapons display then, and it generated a lot of interest.
The new gun was not without its faults. These revealed themselves in Vietnam. Its first combat use was with the U.S. Marines. The M60 was considered heavy when hand-held, although it was one of the lightest machine guns available then. It was not well balanced and was awkward to carry for extended lengths of time. In extreme conditions it could jam during heavy firing, especially when dirty. There were failures to extract and cases could stay stuck in the chamber. That would usually require ramming a cleaning rod down the barrel from the muzzle, or even changing out the barrel. The rotating bolt often required stoning of burrs and roughness on the lugs. If this was not properly done it could cause headspace problems, case stretching and case head separations with often dangerous consequences. There were also problems with the barrel latch catching on clothing, causing the barrel to fall out. This early latch was replaced with a push button type, but many of the older guns still had the old troublesome latch.
Yet another problem was that the grip and trigger housing assembly retaining pins were held in place with somewhat flimsy leaf spring clips. This caused knowledgeable gun crews to use duct tape or cable ties to be sure the clips didn’t break loose and let the pins walk out when the gun was fired. The sear in the trigger group could wear down, causing a runaway gun. A second sear notch was later added to the operating rod to prevent this from causing unfortunate surprises. Extensive wear could also allow the bolt cap retaining pin to fall out. The bolt cap could then unscrew and cause a malfunction.
In time, most of these problems were finally ironed out and successive tweaks and modifications resulted in a very reliable gun. In addition to the integral bipod on the gun, The M91 and M122 tripod mounts became available. These gave the gun stability and repeatable fields of fire. Variants that provided improvements and enabled special applications included M60 (basic early model), M60E1 (experimental), M60E2 (vehicle mounted and electrically fired), M60B (used in helicopters unmounted), M60C (used in aircraft with fixed mounts), M60D (pintle-mounted in helicopters), M60E3 (lightweight variant in 1980s), M60E4 and Mk43 Mod 0/1 (improved specialized use for ground troops and Navy), and M60E6 (lightweight version of the M60E4).
The M60 and its variants were primarily produced by the Saco Defense System Division of Maremont Corporation and U.S. Ordnance from 1957 to 1991, when they began to be phased out in favor of the M240 machine guns. Vital specifications: Weight 23.15 lbs. Length 43.5 inches. Barrel length 22 inches. Muzzle velocity 2,800 feet per second. Effective firing range 1,200 yards.
In typical combat use, M60 machine gun belts were loaded with four ball-type (M80) or armor-piercing (M61) rounds for each tracer (M62) round. This four-and-one mix gave the gunner visual confirmation of where his rounds were headed, and allowed quick adjustment of fire.
The standard infantry version of the M60 had a slot on the left side to hold a reinforced canvas bag which could hold a 100-round belt of ammo that could be directly fed into the gun. This was commonly called the “assault bag.” A padded sling was standard equipment for the gun. It was used for carrying in the ready position, and allowed for engagement while standing, crouching or walking and shooting from the hip or shoulder. An asbestos (later aramid) mitt for barrel changing and spare barrels were also provided for each gun.
In Vietnam, the M60 was given the nickname “the pig” because of its bulk, awkwardness, weight and its ability to eat up ammunition. Linked-ammo carriers were told that they had to “keep the pig fed.” That nickname stuck and even today many will easily recognize it. And yes, pigs did fly in those days! Chopper door gunners put them to very good use.
While civilian purchase of a full-automatic M60 is possible, transferrable guns are scarce and very expensive, of course requiring a lot of government paperwork and waiting. Some semiautomatic versions are being made as of this writing by several companies, with prices running in the $15,000 range. These mimic the more reliable later versions of the gun, and some are equipped with Picatinny rails for mounting optical sights.
Since its inception, the M60 machine gun has been used by over 60 nations and many other entities. It is currently in service in 19 countries. Some are still retained in the inventories of a number of special U.S. military units. “The pig” has proved its worth in many conflicts, and although it was cursed in its early configurations, today it is praised by many and regarded as one of the finest machine guns of all time.
(c) 2022 JLM
John
The U.S. M60 machine gun
During World War II United States armed forces found themselves facing an incredibly versatile and effective machine gun fielded by Germany. This was the MG42, which with its very rapid rate of fire earned the nickname “buzzsaw” on the battlefields of Europe. While we had some fine machine guns, none had the rate of fire, portability, and ease of maintenance exhibited by that Teutonic nightmare.
Shortly after WWII the U.S. Army began experimenting with new machine gun designs. They used the MG42 and the FG42 (an even lighter selective fire machine gun designed for paratroopers in Germany) as examples of more modern technology. Attempts to convert these 8mm guns into similar .30-06-chambered U.S. machine guns by the Saginaw Steering Gear division of General Motors were largely unsuccessful. However, the objective remained to ultimately find a single replacement for the M1917, M1919A4 and M1919A6 machine guns then in use as well as the Browning Automatic rifle. These efforts continued.
What evolved in the 1952-1957 period was an interesting combination of newer concepts such as stamped sheet metal components and a belt feed mechanism using a single pawl similar to that used in the MG42. Also developed for evaluation was a quick-release barrel changeout system. A pistol grip enabled hand-held operation when necessary. A semi-“bullpup” placement of the operating rod and buffer in the shoulder stock was used, much like the FG42. This feature allowed a shorter overall length. The gas-powered operating rod turned a rotating bolt similarly to the FG42 and the earlier American-designed Lewis machine gun. The gas operation utilized the “gas expansion and cutoff” principle that was also employed in the M14 rifle. It was relatively simple and easier to clean.
These experimental designs all fired from an open bolt to aid in better barrel cooling. It was decided that with a quick-change barrel, the barrel would be air-cooled rather than using an obsolete water-cooling jacket. Like the M14 rifle, the new machine gun would be chambered for the 7.62x51mm NATO round which was shorter than the 30-06 round that preceded it. It would have a cyclic rate of fire of approximately 500 to 650 rounds per minute and be fed from a 100 to 250-round disintegrating metallic split-link belt. Overall, the gun would be designed to enable mass production, unlike earlier U.S. machine guns that used many parts that required extensive and expensive machining.
At the time of the M60’s development, there were competing designs such as the Belgian FN MAG and the German Rheinmetall MG3. These were evaluated, but a U.S. design was preferred to avoid the extra expense of foreign entanglements. The final experimental version was designated as the T161E3.
The M60 machine gun was formally adopted as standard in January1957, replacing previous machine guns and the M1918A2 BAR. It was first issued to units in 1959. In my Army unit in that time period, we did not acquire them until 1961. I personally showcased one of the new machine guns to interested civilians during a weapons display then, and it generated a lot of interest.
The new gun was not without its faults. These revealed themselves in Vietnam. Its first combat use was with the U.S. Marines. The M60 was considered heavy when hand-held, although it was one of the lightest machine guns available then. It was not well balanced and was awkward to carry for extended lengths of time. In extreme conditions it could jam during heavy firing, especially when dirty. There were failures to extract and cases could stay stuck in the chamber. That would usually require ramming a cleaning rod down the barrel from the muzzle, or even changing out the barrel. The rotating bolt often required stoning of burrs and roughness on the lugs. If this was not properly done it could cause headspace problems, case stretching and case head separations with often dangerous consequences. There were also problems with the barrel latch catching on clothing, causing the barrel to fall out. This early latch was replaced with a push button type, but many of the older guns still had the old troublesome latch.
Yet another problem was that the grip and trigger housing assembly retaining pins were held in place with somewhat flimsy leaf spring clips. This caused knowledgeable gun crews to use duct tape or cable ties to be sure the clips didn’t break loose and let the pins walk out when the gun was fired. The sear in the trigger group could wear down, causing a runaway gun. A second sear notch was later added to the operating rod to prevent this from causing unfortunate surprises. Extensive wear could also allow the bolt cap retaining pin to fall out. The bolt cap could then unscrew and cause a malfunction.
In time, most of these problems were finally ironed out and successive tweaks and modifications resulted in a very reliable gun. In addition to the integral bipod on the gun, The M91 and M122 tripod mounts became available. These gave the gun stability and repeatable fields of fire. Variants that provided improvements and enabled special applications included M60 (basic early model), M60E1 (experimental), M60E2 (vehicle mounted and electrically fired), M60B (used in helicopters unmounted), M60C (used in aircraft with fixed mounts), M60D (pintle-mounted in helicopters), M60E3 (lightweight variant in 1980s), M60E4 and Mk43 Mod 0/1 (improved specialized use for ground troops and Navy), and M60E6 (lightweight version of the M60E4).
The M60 and its variants were primarily produced by the Saco Defense System Division of Maremont Corporation and U.S. Ordnance from 1957 to 1991, when they began to be phased out in favor of the M240 machine guns. Vital specifications: Weight 23.15 lbs. Length 43.5 inches. Barrel length 22 inches. Muzzle velocity 2,800 feet per second. Effective firing range 1,200 yards.
In typical combat use, M60 machine gun belts were loaded with four ball-type (M80) or armor-piercing (M61) rounds for each tracer (M62) round. This four-and-one mix gave the gunner visual confirmation of where his rounds were headed, and allowed quick adjustment of fire.
The standard infantry version of the M60 had a slot on the left side to hold a reinforced canvas bag which could hold a 100-round belt of ammo that could be directly fed into the gun. This was commonly called the “assault bag.” A padded sling was standard equipment for the gun. It was used for carrying in the ready position, and allowed for engagement while standing, crouching or walking and shooting from the hip or shoulder. An asbestos (later aramid) mitt for barrel changing and spare barrels were also provided for each gun.
In Vietnam, the M60 was given the nickname “the pig” because of its bulk, awkwardness, weight and its ability to eat up ammunition. Linked-ammo carriers were told that they had to “keep the pig fed.” That nickname stuck and even today many will easily recognize it. And yes, pigs did fly in those days! Chopper door gunners put them to very good use.
While civilian purchase of a full-automatic M60 is possible, transferrable guns are scarce and very expensive, of course requiring a lot of government paperwork and waiting. Some semiautomatic versions are being made as of this writing by several companies, with prices running in the $15,000 range. These mimic the more reliable later versions of the gun, and some are equipped with Picatinny rails for mounting optical sights.
Since its inception, the M60 machine gun has been used by over 60 nations and many other entities. It is currently in service in 19 countries. Some are still retained in the inventories of a number of special U.S. military units. “The pig” has proved its worth in many conflicts, and although it was cursed in its early configurations, today it is praised by many and regarded as one of the finest machine guns of all time.
(c) 2022 JLM
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