page_title: 7.62×51mm NATO
section_title: Adoption in battle rifles
hierarchical_section_title: 7.62×51mm NATO / Development / Adoption in battle rifles
caption_attribution_description: English: Home studio shot of the most common pistol and rifle cartridges. From left to right: 7.62×54mmR, 7.62×51mm NATO, 7.62×39mm, 5.56×45mm NATO and 5.45×39mm.
context_page_description: The 7.62×51mm NATO is a rimless bottlenecked rifle cartridge developed in the 1950s as a standard for small arms among NATO countries. It is sometimes confused with the similarly named Russian 7.62×54mmR cartridge, a slightly longer, rimmed cartridge.
  It was introduced in U.S. service in the M14 rifle and M60 machine gun in the late 1950s. The M14 was superseded in U.S. service as the infantry adopted the 5.56×45mm NATO M16 rifle. However, the M14 and many other firearms that use the 7.62×51mm NATO round remain in service, especially in the case of various marksman/sniper rifles, medium machine guns/general-purpose machine guns such as the M240, and various rifles in use by special operations forces. The cartridge is used both by infantry and on mounted and crew-served weapons mounted to vehicles, aircraft and ships.
  Although not identical, the 7.62×51mm NATO and the commercial .308 Winchester cartridges are similar enough that they can be loaded into rifles chambered for the other round, but the Winchester .308 cartridges are typically loaded to higher pressures than 7.62×51mm NATO service cartridges.
context_section_description: The T44 rifle was adopted as the M14 rifle in 1957. Around the same time Britain and Canada adopted the Belgian FN FAL (L1A1 SLR British) as the L1 followed by the West German army designated as the G1. The Germans soon transitioned to a modified version of the Spanish CETME rifle by Heckler & Koch that was adopted as the G3. With all of these firearms, it was clear that the 7.62×51mm NATO could not be fired controllably in fully automatic because of recoil. Both the M14 and FAL were later modified to limit fully automatic selection through semi-automatic versions or selector locks. Efforts were also made to improve control with bipods or heavier barrels.
  While this was going on, the U.S. Project SALVO concluded that a burst of four rounds into a 20-inch (51 cm) circle would cause twice the number of casualties as a fully automatic burst by one of these rifles, regardless of the size of the round. They suggested using a much smaller, .22 caliber, cartridge with two bullets per cartridge (a duplex load), while other researchers investigated the promising flechette rounds that were lighter but offered better penetration than even the .30-06.
  When the M14 arrived in Vietnam, it was found to have a few disadvantages. The rifle's overall length was not well suited for jungle warfare. Also, the weight of 7.62×51mm NATO cartridges limited the total amount of ammunition that could be carried in comparison with the 7.62×39mm cartridge of the Type 56 and AK-47 rifles, with which the Vietcong and North Vietnamese Army soldiers were equipped. In addition, the originally issued wooden-stocked versions of the M14 were susceptible to warping from moisture in tropical environments, producing "wandering zeroes" and other accuracy problems, which caused the adoption of fiberglass stocks.
  Fighting between the big-round and small-round groups reached a peak in the early 1960s, when test after test showed the .223 Remington cartridge fired from the AR-15 allowed an eight-soldier unit to outgun an 11-soldier unit armed with M14s at ranges closer than 300 meters. U.S. troops were able to carry more than twice as much 5.56×45mm ammunition as 7.62×51mm NATO for the same weight, which allowed them an advantage against a typical NVA unit armed with Type 56-1s.
  In 1964, the U.S. Army started replacing their M14s with M16s, incurring another series of complaints from the British. Regardless of the M14 having disadvantages in jungle warfare, 7.62×51mm NATO rifles stayed in military service around the world due to several factors. The 7.62×51mm NATO has proved much more effective than 5.56×45mm at long ranges, and has since found popularity as a sniping round. For instance, M14 variants such as the Mk 14 Enhanced Battle Rifle and M25 Sniper Rifle were utilized in the United States military as designated marksman and sniper rifles. Shorter, easier-to-handle 7.62mm rifles like the Heckler & Koch G3 stayed in service due to their accuracy, range, cartridge effectiveness and reliability.
caption: Service rifle cartridges loaded with projectiles: (left to right) 7.62×54mmR, 7.62×51mm NATO, 7.62×39mm, 5.56×45mm NATO, 5.45×39mm
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