General Purpose Machine Gun (GPMG)
The M60 was once the primary squad support machine gun of the United States military, since replaced by the M240 and M249.
Authored By: Dan Alex | Last Edited:
The M60 served as the primary American general purpose machine gun for a good part of the 20th Century, being fielded in the squad support and vehicle mounted roles during its tenure. The M60 appeared following the close of the Korean War. It entered service in 1957 and saw extensive use in all United States branches from 1960 on. During the Cold War and thereafter, the M60 became a fixture of combat actions encompassing the Vietnam War, the Cambodian Civil War, the Gulf War of 1991, the War in Afghanistan and the Iraq War of 2003 (among others). Some foreign forces today still rely on the firepower inherent in the M60 - this some 50 years since the introduction of the weapon - and some 25+ nations have taken to field the system as their standard multi-purpose machine gun at one point or another. Despite its deficiencies, the M60 has led a long operational life that few modern machine guns can match.
The M60 actually had its origins in several respected German machine guns of World War 2. The excellent belt-fed MG42 was a standard part of the German Army from 1942 to 1959, replacing the expensive yet equally-successful MG34 general purpose machine gun. The MG42 was noted for its in-the-field reliability, ease of use and its durability under true fire conditions - able to spew out an impressive 1,200 to 1,500 rounds per minute. So well-known was the MG42 that American GIs developed an ear for its distinct sound when it fired, recognizing the weapon almost instantly.
The relatively advanced FG42 served the German military as a paratrooper's selective-fire automatic rifle and from 1942 to 1945. Though limited in outright numbers, its combination of size (no bigger than even the standard German Kar 98K bolt-action rifle) and firepower made it a highly portable and yet lethal battlefield implement.
To these ends, American engineers at Saco Defense utilized a modified form of the feed system of the MG42 and the bolt and locking system of the FG42 when designing their new machine gun to a new US Army requirement. The American prototype model became the "T44", retaining some of the look of her German predecessors including the long, squared-off stock, pistol grip and forward-placed bipod assembly. The pistol and trigger group were situated near the middle of the overall design with a ribbed handgrip just ahead. The belt feed mechanism was set off to the left side of the upper portion of receiver. A new easier-to-maintain gas system was developed and fitted to the design. The barrel was specifically designed for quick-changing in the field, denoting its sustained fire role where overheating of the barrel was a sure possibility. Of note here is that this Saco design (becoming the M60) became the first American machine gun to feature the quick-change barrel.
It is also noteworthy that the Americans attempted to outright copy the German MG42 during the war, producing the T24 Machine Gun prototype by Saginaw Steering Gear. However, when it was feared that the cartridge could prove too powerful for the copied design, the project was abandoned in whole.
The T44 was evaluated alongside the competing belt-fed, gas-operated T52 in the 1950s. The T52 was derived from the FG42 itself. The T44 edged out the T52 by way of its reliability under fire and its friendly production make up. The system later received the developmental designation of "T161" before becoming the official "M60" in 1957.
Externally, the M60 has always maintained something of a unique and readily identifiable appearance. Her long stock was squared off, in some ways mimicking the German guns she was based on. The long stock assisted in stability and allowed for a shorter overall weapon. The installation also served as home to the pistol grip and trigger system. The ammunition feed system (for belt ammunition only) was positioned just above the pistol grip with cartridges entering the receiver from the left side and existing out from the right. The ammunition was to be kept in a covered though ventilated container for optimal performance. The rear sight on the receiver was of the flip-up type variety and adjustable while the forward sight only became fully-adjustable later in the M60s production life. The forend served as the forward grip before the addition of a dedicated forward pistol grip debuted in the M60E3. The gas cylinder under the barrel became an identifying characteristic of the M60. The barrel, with its integrated fixed sight, protruded out over the gas cylinder and sported the collapsible integrated bipod assembly, hinged under the barrel itself. The bipod would eventually be relocated apart from the barrel in future M60 forms to help ease barrel changing. Though not the cleanest of designs, the M60 was nonetheless an image born for the utilitarian role it had been designed for.
The M60 weighed in at 23.15lbs and featured an overall length of 43.5 inches, with 22 inches of this made up by the barrel system. The weapon fired the 7.62x51mm NATO cartridge from a gas-operated, open-bolt firing action. The feed system took on the M13-series disintegrating belt and could spew out a rate-of-fire of 600 rounds-per-minute at a muzzle velocity of 2,800 feet per second. Effective range was out to 1,200 yards while maximum range (at the expense of accuracy) was well further.
The M60 made use of several ammunition types in her day. The primary combat cartridge was the M80 Ball which was used in conjunction with the M62 Tracer round in a "four-then-one" arrangement. This meant that for every four M80 Ball rounds fired, a single M62 Tracer round would appear in the circulation, this assisting the operator in aiming his successive shots (called observing the "fall-of-shot") and make the necessary adjustments as needed. While the M80 Ball primarily served to tackle personnel directly, the M61 Armor-Piercing (AP) round was designed to combat light armored vehicles. Training rounds include the M63 Dummy and the M82 Blank - the latter utilized in field exercises and requiring use of a special attachment known as the M13A1 Blank Firing Adaptor (or "BFA") over the muzzle. Ammunition was supplied via the M13 disintegrating metallic split-link belt for all ammunition types, this usually in 100-round count.
As noted in many sources, the M60 was not a weapon without flaw. Many direct operators of the M60 noted a laundry list of items from their past experiences when using the weapon, particularly the early-form M60, and especially when moving on to something newer like the M240 or M249 machine guns. One of the biggest drawbacks of the early M60 was in how the bipod and gas cylinder was attached to the barrel. As these systems were design for squad support action in the sustained fire role, the changing of the barrel was expected for optimal performance (to prevent overheating). As such, the barrel needed to be replaced within time. By the removing the barrel, however, the bipod and gas-cylinder were removed as well, leaving no visible means of support for the operator to brace the weapon on during the barrel changing process. Most 'gunners were forced to hold the M60 up while changing the barrel. As expected, the extra barrel came equipped with its own bipod and gas cylinder attachments, making a simple barrel change a clunky and time-consuming procedure. To add insult to injury, the barrel featured no handle to grasp during the procedure, leading to the issuing of bulky asbestos gloves as a standard part of the field goods. The gloves served to protect the user from handling the hot barrel but also added yet another tool to the complicated M60 kit. Mind you that an M60 operator, if having lost this asbestos glove, was at a distinct disadvantage when "things" hit the fan.
Other reports showcased the weapon's cheap sheet-metal stamp work, this over the receiver and making up the feed tray system. The gas piston was also non-adjustable as a fixed regulator was used instead. The sight system was off-noted as poor with the forward non-adjustable sight fixed to the barrel while the rear sight needing readjusting after each barrel change. The charging handle was somewhat weak and known to break in the heat of combat. The bolt and rod assembly would most assuredly destroy one another over time through constant though typical use.
Though the M60 tested out relatively fine in her controlled evaluations, this including the firing of thousands of rounds of ammunition without issue, in-the-field actions most certainly brought out the worst in any weapon - no matter the pedigree.
As a general purpose light machine gun, it became little surprise to anyone that the M60 reached as many military-based platforms as she did during her tenure. Not only serving as a squad support weapon alongside infantry squads, the M60 could be fielded on naval patrol boats, naval vessels of size, helicopters, fixed-wing aircraft, wheeled vehicles (armored and unarmored) and tracked vehicles to include both armored fighting vehicles and main battle tanks.
In theory, the M60 could be fired from a variety of positions as assumed by the operator. This included firing from the shoulder, from the prone position or "from the hip". In practice, the latter was best reserved for Hollywood and its John Rambo exploits. Any trained soldier would see to it that he make himself as small a target as possible. Additionally, firing from the hip did not produce the most accurate of results. The M60 could make use of its standard integrated bipod assembly for stability or be fielded with a collapsible tripod instead. As a general purpose machine gun, the M60 became equally adept for the offensive or defensive role in support of infantry teams and the like, often times called to target enemy infantry directly or enemy machine gun teams.
"M60" came to signify the machine gun in its original form as well as refer to the entire family line of M60-related machine guns. M60 was the designation of the basic model of 1957.
The M60E1 was an improved form of the base M60 but was not selected for mass production. A handle was finally added to the barrel and the gas assembly and bipod were now made separate from the barrel assembly itself, easing barrel changes. The M60E1 became the first major revision of the base M60 and therefore its first true variant.
The M60E2 became an electrically-fired, vehicle-mounted co-axial version of the base M60 machine gun. Its usefulness was apparent in such systems as main battle tanks and armored fighting vehicles. The co-axial version was generally a stripped-down variant made specifically for the installation into vehicles - most often times in the forward turret wall alongside the main armament and operated by a designated gunner or commander (depending on the vehicle). As can be expected, these weapons vented their dangerous gasses outside of the vehicle and therefore sported revised and elongated gas cylinders. The M60E2 was replaced by the co-axial version of the M240 GPMG (based on the Belgium FN MAG).
The M60B was used for a short time in "free-floating" positions in defense of helicopters, essentially M60 guns held in hand by onboard gunners. The bipod was removed for the role and a different stock affixed. This arrangement allowed for the operator to maintain a pretty hefty field of fire from his lofty position. The M60B was, however, replaced by the M60D which made use of a pintle-mount assembly.
The M60C "Flexible Machine Gun" was used in fixed forward-facing mountings on helicopters and close-support fixed-wing aircraft. The C-model had her sights, pistol grip and bipod assembly removed for the role and eventually proved highly adaptable across different aerial platforms. A hydraulic swivel system was utilized as was an electronic control system and the firing action was controlled from within the cockpit. The M60C could sustain a rate-of-fire equaling 500 to 650 rounds per minute. On the UH-1B Huey helicopter, the M6 and M16 armament subsystem were used in conjunction with the M60C. On the OH-13 Sioux and OH-23 Raven platforms, the M2 armament subsystem was used instead. Some 563 M60C examples were produced.
The M60D "Flexible Machine Gun" was brought online as a pintle-mounted version to replace the pre-existing M60B production models and primarily used for door gunnery in helicopter cabins. The M60D made use of spade grips with a ring-type gunsight not unlike those used in World War 2 bombers such as the Boeing B-17 Flying Fortress. The ammunition feed system was revised for the role and included a canvas bag to collect spent cartridges and link parts (the latter more of a safety concern considering the delicate nature of rotary aircraft - blades and turbines alike). The M60D saw extensive use on UH-1 Huey, CH-47 Chinook and UH-60 Blackhawk helicopters during her tenure. The M240H was developed to replace the M60D.
The Maremont Lightweight Machine Gun M60 was developed by Saco Division, Maremont Corporation of Maine to provide for a lighter and, therefore, more versatile version of the M60E1. The bipod was affixed to the receiver and a carrying handle was installed onto the barrel itself to also double as a barrel-changing hand grip. A forward pistol grip was installed along the forward section of the weapon. The feed system was revised to simplify charging and a heat shield replaced the original forward design. The front sight was now made fully-adjustable and the gas system simplified. Though not selected for production itself, the Maremont M60 went on to become the foundation for the development of the production M60E3.
In the mid-1980's, the M60E3 was introduced as a "lightened" and updated form of the M60 family line and was the first real departure from the base design. It featured the changes listed above for the Maremont M60 - the bipod was now connected to the receiver itself while the identifiable forward pistol grip was fitted under the forend. A new and improved gas system was instituted as were an ambidextrous safety and universal attachments for a variety of slings. A barrel-mounted carrying handle rounded out the list and doubled as the barrel-changing handle. A revised trigger guard allowed the operator to fire the gun with a gloved hand. However, the barrel was lightened at the expense of the amount of ammunition that could be fired during the sustained fire role, requiring frequent barrel changes as a result. Two barrels - a "short assault" and a "heavy sustained fire" - were issued. While these changes were intended for the positive, it was soon realized that the weight loss of the M60E3 contributed to the fragility of the system in the long run. The durability of the machine gun came into question as the lighter components were shown to wear down or even break more easily than before. Nevertheless, the M60E3 still found a home as a marketable and useful product for those looking to upgrade or compliment their existing collections of M60s.
The M60E4 light machine gun was an altogether improved multi-purpose machine gun developed in the 1990s and shared some similarities with the "lightened" M60E3. The M60E4 was advertised as a more reliable system when compared to the earlier M60 incarnation and could also be modified to fulfill a variety of battlefield roles including that of a co-axial weapon on vehicles. The M60E4 was fielded with three different barrel types - a short lightweight assault, a short heavy sustained fire and a long heavy sustained fire barrel. A revised feed system improved reliability, particularly in how the M60 lifted the ammunition belt into action. However, the M240B (previously the M240E4) was developed as the M60E4 equivalent and selected by the US Army instead. The United States Navy SEALs nevertheless fielded the M60E4 under the designation of "Mk 43 Mod 0" to replace their aging M60E3 assault models. The Mk 43 Mod 0 sported a shorter barrel and multiple accessory attachments in line with the M60E3 before it.
The M60 in Vietnam
Like other weapons in the Vietnam conflict, the M60's sophisticated design and complicated construction often led to an unreliable weapon considering the rigors of combat and the generally disagreeable nature of jungle warfare. The environment played havoc on the internal systems of the M60 and keeping her clean became an instant priority to any M60 crew. Sand proved a major culprit in causing jams within the weapon and general maintenance proved a headache for most. The original M60 quickly fell out of favor with US Marines - owing their dislike to the permanent attaching of the bipod, barrel and gas cylinder assemblies. The M60E1 attempted to rectify this and itself became a respectable and feared opponent within time. A standard infantry company was issued six M60 systems.
Beyond the squad support role, the M60 was fielded just about anywhere there proved a defensive or offensive need. The PBR (Patrol Boat, River) and like water-borne vessels featured the M60 on pintle mountings and behind shields, ready to supply its hefty rate-of-fire to an area or designated target. Huey helicopters took to operating M60s in quad-mountings, two to a fuselage side, with inboard-mounted rocket pods to boot (this often complimented by door-mounted M60 systems as well). This arrangement turned the durable transports into full-fledged gunships that could bring rain down onto North Vietnamese positions.
If the M60 maintained any advantages, it was in her basic design philosophies. She was a relatively cost-effective solution, firing a NATO-standard round that was available in number, and she yielded a good rate-of-fire from a hefty ammunition pouch. Despite her being regarded as a heavy weapon for lugging around, she was in fact one of the lighter general purpose machine guns in use at the time. Like the M16, the M60 may have deserved its bad reputation in the Vietnam War but this is not to say that she did not have her optimal uses - or that she failed to save the lives of countless American GIs through her available strengths. But we leave this argument to those respected veterans to decide. At the very least, the M60 was not another French-based "Chauchat" for American use.
The Beginning of the End
The M60 was more-or-less replaced in US military service by the M240 general purpose machine gun, this based on the Belgium Fabrique Nationale FN MAG 58 model. The M240 also fires the 7.62x51mm NATO cartridge through a gas-operated, open bolt action. The weapon entered service in 1977 and is gradually overtaking (along with the M249 based on the Belgium FN Minimi) the roles once held by the M60.
The M60 in Pop Culture
The M60 has seen some action in pop culture as well, appearing as Rambo's weapon-of-choice at the conclusion of the motion picture "Rambo, First Blood" (utilizing the base M60) and "Rambo, First Blood, Part II" (having upgraded to the M60E3). Actor and martial arts star Chuck Norris puts an M60 to good use in his return to Vietnam as Colonel James Braddock in the motion picture "Missing in Action".