Work that would eventually develop the 7.62×51mm NATO started just after World War I when the large, powerful .30-06 Springfield cartridge proved difficult to adapt to semi-automatic rifles.

Thus when war appeared to be looming again, only a couple of decades later, the .30-06 Springfield was the only round available, and the M1 Garand provided U.S. troops with greater firepower than their bolt action-armed opponents.

One of the most common complaints was the limited-capacity, eight-round en-bloc clip, and many experimental designs modified the weapon with a detachable box magazine.

The test program continued for several years, including both the original .30-06 Springfield round and experimental cartridges.

During the 1940s, the .300 Savage became the basis for experiments on behalf of the U.S. Military that resulted in the development of the T65 series of experimental cartridges.

They had spent considerable time and effort developing the intermediate-power .280 British (7 mm) cartridge with an eye towards controllable fully automatic fire.

The chamber of the former has a marginally shorter headspace and thinner case walls than the latter due to changed specifications between 1952 and 1954.

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.

Both the M14 and FAL were later modified to limit fully automatic selection through semi-automatic versions or selector locks.

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.

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.

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.

Shorter, easier-to-handle 7.62mm rifles like the G3 stayed in service due to their accuracy, range, cartridge effectiveness and reliability.

They used heavier and more aerodynamic bullets that had a higher ballistic coefficient than standard ball rounds, meaning they shed velocity at longer ranges more gradually.

[11] Maintaining velocity is important for accurate long-range shots because dropping from supersonic to transonic speeds disturbs the flight of the bullet and adversely affects accuracy.

[12] The 7.62×51mm NATO round remains in use in designated marksman rifles such as the Heckler & Koch HK417, SIG 716, FN SCAR, L129A1, Colt Canada C20 DMR and LMT MARS-H based riles to take advantage of the effective range and accuracy potential compared with intermediate rifle rounds.

West Germany rechambered many of its WW2-era MG42s to create the MG2, and the succeeding MG3 is essentially a slightly modified version of the same weapon.

These have been replaced to a considerable extent in the light machine gun role by 5.56×45mm NATO weapons, such as the widespread use of the M249 SAW, but the 7.62×51mm NATO fully powered cartridge is still the standard chambering for the M134 Minigun and GPMGs such as the M60E4, FN MAG/M240, HK21, MG3, AA-52, Vektor SS-77, UKM-2000 and MG5 and flexible mountings such as helicopters, jeeps, and tanks.

The bullet is redesigned with a copper jacket and exposed hardened steel penetrator, eliminating 114.5 grains (7.4 g) of lead with production of each M80A1 projectile.

[20][19] The U.S. Special Operations Command plans to begin fielding of the 6.5mm Creedmoor cartridge in early 2019 to replace the 7.62×51mm NATO round in semi-automatic sniper rifles.

The same rifles can use the new cartridge, as their similar dimensions allow the same magazines to be used and the weapon only requires a barrel change.

This shorter cartridge allows a slight reduction in the size and weight of firearms that chamber it, and better cycling in automatic and semi-automatic rifles.

[75] Radway Green, which is currently owned by BAE Systems, continues to produce ammunition for the Ministry of Defence and export customers.