page_title: M60 machine gun
section_title: Design flaws
hierarchical_section_title: M60 machine gun / Design / Design flaws
caption_attribution_description: Spec. Tracy Burgett, 810th Military Police Company, mans a 7.62mm M60 machine gun atop an M998 High-Mobility Multipurpose Wheeled Vehicle (HMMWV) during Operation Desert Shield.
context_page_description: The M60, officially the United States Machine Gun, Caliber 7.62 mm, M60, is a family of American general-purpose machine guns firing 7.62×51mm NATO cartridges from a disintegrating belt of M13 links. There are several types of ammunition approved for use in the M60, including ball, tracer, and armor-piercing rounds.
  It was adopted in 1957 and issued to units beginning in 1959. It has served with every branch of the U.S. military and still serves with the armed forces of other states. Its manufacture and continued upgrade for military and commercial purchase continues into the 21st century, although it has been replaced or supplemented in most roles by other designs, most notably the M240 machine gun in U.S. service.
context_section_description: At the time of the M60's development, other designs, like the Belgian FN MAG and the German Rheinmetall MG 3 (MG42 derivative) had yet to enter production. In Army tests, the M60 proved fairly effective, but in the jungles of Southeast Asia it displayed a number of troubling issues.
  A common complaint was the weapon's weight; though the M60 was among the lightest 7.62 mm machine guns of the era, the weapon was poorly balanced, and thus awkward to carry for long periods. The single most common complaint was that the M60 was unreliable in extreme conditions and prone to jamming and other malfunctions during heavy firing, especially when it was dirty. Sometimes spent casings would fail to extract, and stay stuck inside the chamber, forcing a barrel change before it could be fired again. The humidity and mud of the jungles combined with powder fouling and grease or oil in the action of the M60 to produce severe stoppages unless it was kept dry and thoroughly cleaned with solvent after each engagement, a difficult proposition for many units. The M60 did best in aerial and static-defense roles where it could be stored in controlled conditions and regularly maintained by skilled personnel.
  Due to the rotating bolt design, the M60 required stoning of burrs or roughness on the lugs, which could increase headspace, occasionally causing cartridge case stretching and head separation. This required replacement of the bolt. The M60 sometimes (depending on the version) tore off the rims from fired cartridge cases during the extraction cycle, causing a jam that required a cleaning rod to be rammed down the barrel to extract the torn cartridge, a potentially deadly procedure while under fire in combat. The barrel latch mechanism (a swinging lever) could catch on the gunner's equipment and accidentally unlatch, causing the barrel to fall out of the gun. On new M60s, the lever was replaced with a push button mechanism that was less likely to be accidentally released, but few of the older M60s were modified due to expense, with many of the extant weapons still bearing them.
  The grip/trigger housing assembly is held in place with a rather fragile leaf spring clip instead of the captive pins used in other designs. The spring clip has been known to be prone to breakage since the first trials at Aberdeen Proving Ground. Duct tape and cable ties have been seen on M60s in the field, placed there by their crews in case the spring clip breaks. The sear in the trigger mechanism gained a reputation for wearing down, and a malfunction could cause the gun to "run away". A second sear notch was eventually added to the operating rod to reduce the chance of this happening.
  Several critical parts of early production M60s, such as the receiver cover and feed tray, were made from very thin sheet metal stampings and were prone to bending or breaking; sturdier parts were eventually introduced in the early 1970s. Early M60s also had driving-spring guides and operating rods that were too thin, and gas pistons that were too narrow behind the piston head (part of an attempt to save weight), leading to problems with breakages. Metallurgical problems also played a part, (blamed by some on low-bid contractors), but after 1970 a slightly heavier part was designed and slowly put into the supply chain. High-round-count weapons were also susceptible to stretching of the receiver and other parts.
  Another major criticism of the M60 was the inseparability of the barrel from the gas system regulator and the bipod. The sole advantage of the fixed regulator was preventing the operator from inadvertently damaging the weapon by setting the gas pressure too high, though this actually proved to be a major disadvantage in combat; the lack of an adjustable regulator also prevented the gunner from combating progressive fouling of the gas system by increasing the pressure to compensate. The result was insufficient gas power to operate the action after lengthy periods of fire, a situation only remedied by a full field strip of the weapon and cleaning the gas system with solvent and pip
caption: A soldier from the 810th Military Police Company mans a 7.62 mm M60 machine gun atop an M998 Humvee during the Persian Gulf War's Operation Desert Shield.
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