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 Post subject: Caliber Review > 7.62x51mm NATO

Sharp Shooter

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The purpose of creating this thread here is to explore one of the most definitive caliber in military history - the 7.62x51 NATO along with the platforms available for this caliber. All senior and experienced members are requested to chip in with their inputs regarding this caliber in this thread.

I will be using different online sources for compiling the information being posted below and mentioning the links of the sources wherever necessary.


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7.62x51mm NATO > Caliber Review


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The 7.62x51mm NATO (official NATO nomenclature 7.62 NATO) is the rifle cartridge developed in the 1950s as a standard for small arms among NATO countries. When loaded with a bullet design that expands, tumbles, or fragments in tissue, this cartridge is capable of delivering good terminal performance. Proponents of the hydrostatic shock theory contend that this includes remote wounding effects known as hydrostatic shock.

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 The M14 was superseded in U.S. service as the infantry adopted the 5.56x45mm NATO M16. However, the M14 and many other firearms that use the 7.62×51 round remain in service, especially in the case of sniper rifles and machine guns. The cartridge is used both by infantry and on mounted and crew-served weapons mounted to vehicles, aircraft and ships.

It would be appropriate to address here the oft-posed question "Are the .308 Winchester and 7.62x51 NATO one and the same?" Here's the straight scoop. The simple answer is no. There are differences in chamber specs and maximum pressures.

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The SAMMI/CIP maximum pressure for the .308 Win cartridge is 62,000 psi, while the 7.62x51 max is 50,000 psi. Also, the headspace is slightly different. The .308 Win "Go Gauge" is 1.630" vs. 1.635" for the 7.62x51. The .308's "No-Go" dimension is 1.634" vs. 1.6405" for a 7.62x51 "No Go" gauge. That said, it is normally fine to shoot quality 7.62x51 NATO ammo in a gun chambered for the .308 Winchester (though not all NATO ammo is identical). Clint McKee of Fulton Armory notes: "[N]obody makes 7.62mm (NATO) ammo that isn't to the .308 'headspace' dimension spec. So 7.62mm ammo fits nicely into .308 chambers, as a rule." You CAN encounter problems going the other way, however. A commercial .308 Win round can exceed the max rated pressure for the 7.62x51. So, you should avoid putting full-power .308 Win rounds into military surplus rifles that have been designed for 50,000 psi max.


CALIBER OVERVIEW

The cartridge itself offers similar ballistic performance in most firearms to the .30-06 Springfield that it replaced in U.S. service. Though shorter, standard loadings fire similar bullet weights at similar velocities. Modern propellants allowed the same velocity from a case with less capacity. The smaller case requires less brass and yields a shorter cartridge. This shorter cartridge allows a reduction in the size of the firearms that chamber it.

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Specifications

Parent case : .308 Winchester (derived from the .300 Savage)
Case type: Rimless, Bottleneck
Bullet diameter: 7.82 mm (0.308 in)
Neck diameter: 8.77 mm (0.345 in)
Shoulder diameter: 11.53 mm (0.454 in)
Base diameter: 11.94 mm (0.470 in)
Rim diameter: 12.01 mm (0.473 in)
Rim thickness: 1.27 mm (0.050 in)
Case length: 51.18 mm (2.015 in)
Overall length: 69.85 mm (2.750 in)
Rifling twist: 1:12"
Primer type: Large Rifle
Maximum pressure: 415 MPa (60,200 psi)


DEVELOPMENT

Work that would eventually develop the 7.62×51mm NATO started just after World War I when it became clear that the large, powerful .30-06 cartridge was difficult to adapt to semi-automatic rifles. A less-powerful cartridge would allow a lighter firing mechanism. At the time the most promising design was the .276 Pedersen. When it was eventually demonstrated that the .30-06 was suitable for semi-automatic rifles, the .276 was dropped.

Thus when war appeared to be looming again only a few years later, the .30-06 was the only round available and the M1 Garand provided U.S. troops with greater firepower than their bolt action-armed opponents. The Garand performed so well that the U.S. saw little need to replace it during World War II and the .30-06 served well beyond the Korean War and into the 1960s.

During the 1940s and early 1950s several experiments were carried out to improve on the Garand. One of the most common complaints was the limited capacity en-bloc clip and many experimental designs modified the weapon with a detachable box magazine. Springfield Armory's T20 rifle, was a fully automatic version. Though not adopted, experience with a fully-automatic Garand laid the groundwork for its replacement.

The test program continued for several years, including both the original .30-06 round and a modified .300 Savage (then known as the T65). In the end, the T65 cartridge demonstrated power roughly equal to the original .30-06, firing a 147-grain bullet at 2,750 feet per second (840 m/s) but was approximately .5 inches shorter. The eventual result of this competition was the T44 rifle.

When the United States developed the T65 cartridge, the British took a different route. They had spent considerable time and effort developing the intermediate-power .280 British cartridge with an eye towards controllable fully-automatic fire. Meanwhile, the U.S. held to its desire not to reduce the effectiveness of individual shots. The American philosophy was to use automatic fire for emergencies only and continue to use semi-automatic fire the majority of the time. After considerable squabbling the Canadian Army announced they would be happy to use the .280 only if the U.S. did as well. It was clear the U.S. would not use the .280. The T65 was chosen as the NATO standard cartridge in 1954.

The T44 was adopted as the M14 in 1957. Britain and Canada adopted the FN FAL around the same time followed by West German army as the G1. The Germans soon transitioned to a modified version of the Spanish CETME rifle, Heckler & Koch G3. With all three of these firearms, it was clear that the 7.62mm NATO could not be fired controllably in fully automatic due to recoil. Both the M14s and FAL would later go through several variations intended to either limit fully automatic selection through semi-auto version or selector locks or improve control with bipods and/or heavier barrels.
While all of this was going on, the U.S. Project SALVO concluded that a burst of four rounds into a 20-inch (510 mm) circle would cause twice the number of casualties as a fully automatic burst by one of these battle 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 even lighter but offered better penetration than even the .30-06. These studies were kept secret to prevent the British from using them as evidence in favour of their smaller rounds.

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 cartridges limited the total amount of ammunition that could be carried when compared with the common 7.62×39mm cartridge of the Type 56 assault rifles, which the Vietcong and North Vietnamese Army soldiers were equipped with. 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 (this was fixed with 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 8-soldier unit to outgun an 11-soldier unit armed with M14s. U.S. troops were able to carry almost twice as much 5.56×45mm NATO ammunition as 7.62x51mm for the same weight, which would allow them a better advantage against a typical NVA unit armed with AK-47s. In 1964, the U.S. Army started replacing their M14s with the M16, incurring another series of complaints from the British. Complaints were also registered from the combat troops forced to use the M16, who averred that presuming they could get the rifle to work at all, two and three hits were required to drop one enemy soldier, whereas a single hit from a 7.62 NATO round dropped an enemy every time. The dispute continues today.

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 Mod 0 Enhanced Battle Rifle and M21 are still used 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.

The 7.62×51mm NATO round nevertheless met the designer's demands for fully automatic reliability with a full-power round. It remained the main machine gun round for almost all NATO forces well into the 1990s, even being used in adapted versions of older .30-06 machine guns such as the Browning M1919A4 from the WWII era. 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 FN Minimi, but the 7.62 round is still the standard chambering for most general-purpose machine guns such as the FN MAG and the German MG3, and flexible mountings such as helicopters, jeeps, and tanks.

Winchester Ammunition (a division of the Olin Corporation) saw the market for a civilian model of the T65 cartridge and released it commercially in 1952 as the .308 Winchester, two years prior to adoption of the cartridge by NATO.


MILITARY CARTRIDGE TYPES

Cartridge, Caliber 7.62mm, NATO, Ball, M59 (United States): 150.5-grain 7.62×51mm NATO ball cartridge. A further development of the initial T65 cartridge.

Cartridge, Caliber 7.62mm, NATO, Armor Piercing, M61 (United States): 150.5-grain 7.62×51mm NATO armor-piercing round, black cartridge tip.

Cartridge, Caliber 7.62mm, NATO, Tracer, M62 (United States): 142-grain (9.2 g) tracer cartridge, orange cartridge tip.

Cartridge, Caliber 7.62mm, NATO, Grenade, M64 (United States): 7.62×51mm NATO grenade launching blank.

Cartridge, Caliber 7.62mm, NATO, Ball, M80 (United States): 147-grain 7.62×51mm NATO ball cartridge.

Cartridge, Caliber 7.62mm, NATO, Match, M118 (United States): 173-grain 7.62×51mm NATO Full Metal Jacket Boat Tail round specifically designed for Match purposes. Introduced in 1968 as XM118, standardized in 1970 as M118. Produced at Lake City Army Ammunition Plant.

Cartridge, Caliber 7.62mm, NATO, Ball, Special, M118 (United States): 173-grain 7.62×51mm NATO Full Metal Jacket Boat Tail round specifically designed for match purposes. Produced by Lake City Army Ammunition Plant. This is an interim match round which utilized M80 ball brass with the 173-grain (11.2 g) FMJBT bullet. During this period in the early to late 1980s the performance of the round declined. Powder, primer, brass, bullets were no longer produced in matching lots.

Cartridge, Caliber 7.62mm, NATO, Ball, Special, M118LR (United States): 175-grain 7.62×51mm NATO Hollow Point Boat Tail round specifically designed for long-range sniping. Produced at Lake City Army Ammunition Plant.

Cartridge, Caliber 7.62mm, NATO, Duplex, M198 (United States): 7.62×51mm NATO duplex round with two 84-grain (5.4 g) bullets. The developmental designation was T314E3.

Cartridge, Caliber 7.62mm, NATO, Tracer, M276 (United States): 7.62×51mm NATO so-called "Dim Tracer" with reduced effect primarily for use with night vision devices, green cartridge tip with pink ring.

Cartridge, Caliber 7.62mm, NATO, Match, M852 (United States): 168-grain 7.62×51mm NATO Hollow-Point Boat-Tail cartridge, specifically designed for use in National Match competitions, later approved by US Army JAG for combat use by snipers.

Cartridge, Caliber 7.62mm, NATO, Saboted Light Armor Penetrator (SLAP), M948 (United States): 7.62×51mm NATO Saboted Light Armor Penetrator cartridge.

Cartridge, Caliber 7.62mm, NATO, Armor Piercing, M993 (United States): 126.6-grain 7.62×51mm NATO armor-piercing round, black cartridge tip.

Cartridge, Grenade, L1A1 (United Kingdom): 7.62×51mm grenade launching cartridge with one subvariant (L1A2) with unknown differences.

Cartridge, Ball, L2A1 (United Kingdom): 7.62×51mm ball cartridge, with three subvariants (A2-A4) with unknown differences.

Cartridge, Tracer, L5A1 (United Kingdom): 7.62×51mm tracer cartridge, designed to last out to 1000 meters. Four subvariants exist, with brighter ignition (A2), tracer reduced to 750 meters (A3), with a pistol powder charge (A4), and with improved ballistics (A5).

Cartridge, Ball, L42A1 (United Kingdom): 7.62×51mm ball cartridge, 155 grain round

Cartridge, Ball, L44A1 (United Kingdom): 7.62×51mm ball cartridge, 144 grain round

Cartridge, Caliber 7.62mm, NATO, Ball, F4 (Australia): 144-grain 7.62×51mm NATO ball cartridge. Australian equivalent to U.S. M80 round. In service with the Australian Defence Force.


SOURCES:

http://www.6mmbr.com/308win.html
http://en.wikipedia.org/wiki/7.62x51mm_NATO


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 Post subject: Re: 7.62x51mm NATO > Caliber Review

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The Definitive Military Service Calibre and Rifle For the 21st Century

By Mike Staples

( The article being reproduced here is an extract of the two part article series written by Mike Staples. The complete article can be accessed at http://www.chuckhawks.com/definitive_se ... aliber.htm )


Introduction

Hi, my name is Mike Staples and I am an ex Australian Army Fitter Armament or to put it more simply, an Armourer. My experience takes in all Australian Military Weapons including pistols, rifles, SMGs, LMGs, HMGs, Mortars, recoilless rifle, and artillery pieces, as well as mounted guns in our Armoured vehicles that were current at the time of my service. On top of that experience is my love of shooting, which started when I was around 6 years of age and has continued to this day, some 51 years later. I have been asked by Mr. Hawks to write an article on a suitable calibre for a General Purpose Military Rifle (GPMR), and whilst the calibre is important the delivery system, a.k.a. the rifle, is equally so. That being the case, this first article will establish what I feel is a suitable calibre to replace the 5.56mm NATO round, whilst the second part will put forward suggestions on a suitable rifle.

There has been a multitude of cartridges that have been used by the worlds Military Forces, and to compare all of them in the pursuit of the "perfect calibre" for the 21st Century would take many pages and many hours of research. Therefore, I will concentrate on those which have been used by the US, Australia, Great Britain, and NATO Forces in recent history.

Since the Vietnam War there has been a move to make one calibre "the NATO calibre," and at this point in time that calibre is the 5.56mm NATO. The main reason for this, from my perspective, is to make all aligned forces users of this calibre. NATO is a collage of many countries. When NATO forces either take up arms against an aggressor or have become an occupation force on behalf of the United Nations inside a country that has experienced a war or uprising, many soldiers from different countries make up that force. If all used a different calibre in their GPMR, ammunition re-supply would be a nightmare.

The question is then, "What makes a suitable calibre and why?"

The answer to this question will not be easy to establish, as every country and every soldier has a differing opinion. While some like one calibre and one style of rifle, others have trouble accepting those choices. They may prefer to stay with whatever their country uses, as it has become familiar, comfortable and a trusted friend.

I am told by Mr. Hawks (Chuck Hawks) and some of my Australian Army friends that there are moves afoot to abandon the 5.56mm calibre. (These may, of course, come to nothing--particularly as they originated with the troops, not the high command. -Ed.) Apparently the U.S. Senate is currently considering a new calibre (the 6.8mm SPC) for use by Special Forces. As the actions of the U.S. military have in the past greatly influenced the NATO countries, it is quite likely that whatever is chosen by the U.S. will eventually become the NATO standard.

Before they do, I would like to bring to the attention of the leaders of the NATO countries a calibre which is not only a suitable upgrade, but that eclipses the two best service rounds yet devised.

To do this I must compare the two standard NATO rounds used today (7.62x51mm and the 5.56mm) with what I consider to be the best choice. I will include in these comparisons the .30-06, a world record holder for all ranges prior to the advent of the .308 Winchester (7.62x51 NATO) and which was, over a number of decades, the U.S. calibre of choice.

The .30-06 was brought out in 1906 to replace the original cartridge for the Springfield rifle of 1903, which initially was chambered for the .30-03 round. Both cartridges fired a .30 calibre bullet, but the '03 had a 220 grain monster and a very long neck to accommodate it. The neck of the '06 case was shortened by .07 of an inch and became the standard military cartridge with a 150 grain spitzer projectile. The '03 and '06 signify the year of first use.

This round was used in every .30 calibre weapon in the US armoury up until the late 1950s. These included the M1 Garand, the BAR and their main LMG, the .30 calibre machine gun. At that time the .30-06 was replaced by the ballistically identical but 10% smaller .308 Winchester (7.62mm NATO) cartridge.

Why they ever abandoned these powerful cartridges, exchanging them for the .223 (5.56mm) "squib" used in the M16 Armalite rifle, is anybody's guess. (The official reasons included reducing recoil and facilitating fully automatic fire. -Ed.) That change, as far as I am concerned, did the US soldier a great disservice. More on that in the second part of this article.

Detailed tables will establish my calibre of choice and the reasons for it. The calibres I will compare in this article are as follows:

(1) .30-06 (US design) - .30 calibre, .308" projectile (military calibre)

(2) 7.62 x 51 (.308 Win.) - .30 calibre, .308" projectile (military calibre)

(3) 5.56mm (.223 Rem.) - .22 calibre, .224" projectile (military calibre)

(4) .270 Winchester - .270 calibre, .277" projectile (civilian calibre)

Before I proceed, I would like to clarify "calibre" and the fact that some projectiles appear to be the same size as the calibre.

Calibre is described as being "bore" diameter (inside bore diameter, ID), which is gauged across the lands of the rifling in the bore of a weapon. The diameter of the projectile is usually equal to the "groove" diameter of the bore, measured across the depth of the groves in the bore (outside bore diameter, OD), or in some cases is slightly bigger than the OD of the bore.

This difference, if the projectile is slightly bigger than the distance across the grooves, is possibly only 1 or 2/1000ths of an inch. This is ordinarily only the case when the projectiles are made from a lead-antimony mixture, as these projectiles are soft enough to deform sufficiently to allow the projectile to fit the barrel. I would suggest that all copper clad (jacketed) projectiles would be the same size as the OD of the bore. To be effective, all projectiles must, at the time of firing, "take" the rifling of the weapon, making a gas tight seal.

Some common examples of this differentiation in calibre are the .308 Winchester and the .243 Winchester. The .308 Winchester is in reality a standard .30 calibre cartridge. .308 rifles have a bore diameter of .300" and a groove/bullet diameter of .308". (Both dimensions are identical to the earlier .30-06 and .300 Magnum.)

The .243 Winchester is a similar case and rifles in this caliber have a groove/bullet diameter of .243". Both the .243 and .308 were named for their groove diameter rather than the more traditional bore diameter. This method of nomenclature became popular after the 1950's and many, but not all, cartridges developed since that time have been named for their groove/bullet diameter.

To arrive at a suitable calibre for a GPMR one must take into consideration the following minimum criteria:

(1) Does the selected calibre have minimal bullet drop at ranges out to a minimum of 400 yards (366 metres)?

(2) Is the complete round suitable for self-loading rifles (in overall length)?

(3) Is the projectile heavy enough to deliver sufficient knock down power (Kinetic Energy) at all ranges out to 400 yards?

(4) Will the trajectory of the projectile be relatively flat when compared with other suitable ammunition?

(5) Is a complete round (i.e. cartridge case + projectile + powder + primer) light enough to allow a soldier to carry a minimum of 300 rounds on his person?

(6) Will the selected calibre and projectile be accurate enough to shoot groups of 5 inches/125mm or less at the stipulated minimum range? (The rifle being used will be a factor here.)

(7) Will the selected calibre and projectile be able to attain velocities of at least 3000 FPS from a self loading service rifle?


The following tables clearly demonstrate what round I feel conforms to the above criteria. The comparison rounds are:

(1) The 5.56mm round, using a 63 grain projectile with a MV of 3200 FPS.

(2) The 7.62 x 51 round, using 168 grain projectile with a MV of 2700 FPS (I do not have detailed tables for a MV of 2650 FPS, so I have used a slightly higher MV to highlight the differences).

(3) The 30.06 round using a 150 grain projectile with a MV of 2700 FPS.

(4) A .270 (6.858mm) round using a new case with the same dimensions as the 7.62 x 51 case, except it is necked down to accept a .277" diameter projectile. (A similar situation to the .243, which uses a necked down .308 case). In European (or modern military) nomenclature this would be a 6.85 x 51mm cartridge. 150 grain bullet at a MV of 3000 FPS.

Note: All projectiles are spitzers (pointed) with boat tail base, as I have no tables for FMJ projectiles. All tables, are based on information, as found in the Sierra Reloading Manual, 2nd edition; Sighting plane is assumed to be 1.5 inches above the axis of the bore; All distances are in YARDS. 1 Imperial Yard = (approx.) 0.9143 metres.

Velocity in feet-per-second (Muzzle, 100, 200, 300, 400, 500 yards)

5.56mm NATO (63 grain): 3200, 2862, 2521, 2198, 1900, 1612

7.62 NATO (168 grain): 2700, 2513, 2333, 2161, 1996, 1839

.30-06 (150 grain): 2700, 2473, 2257, 2052, 1859, 1664

.270 Win. (150 grain): 3000, 2804, 2613, 2429, 2253, 2084

Kinetic Energy in Ft-Pounds (Muzzle, 100, 200, 300, 400, 500 yards)

5.56mm NATO (63 grains @ 3200 FPS): 1432, 1146, 889, 676, 505, 364

7.62 NATO (168 grains @ 2700 FPS): 2719, 2355, 2030, 1742, 1486, 1261

.30-06 (150 grains @ 2700 FPS): 2428, 2037, 1697, 1403, 1150, 922

.270 Win. (150 grains @ 3000 FPS): 2997, 2618, 2273, 1965, 1690, 1446

Bullet Drop from line of bore (at 100, 200, 300, 400, 500 yards)

5.56mm NATO (63 grains @ 3200 FPS): -1.76, -7.79, -19.31, -38.06, -66.51

7.62 NATO (168 grains @ 2700 FPS): -2.37, -10.23, -24.47, -46.14, -76.53

.30-06 (150 grains @ 2700 FPS): -2.41, -10.51, -25.42, -48.60, -81.86

.270 Win. (150 grains @ 3000 FPS): -1.90, -8.22, -19.63, -36.92, -61.05

Bullet Path in Inches at Zero Range of 300 yards (100, 200, 300, 400, 500)

5.56mm NATO (63 grain @ 3200 FPS): +3.68, +4.58, 0.00, -11.81, -33.33

7.62 NATO (168 grain @ 2700 FPS): +4.79, +5.58, 0.00, -13.02, -34.75

.30-06 (150 grain @ 2700 FPS): +5.06, +5.94, 0.00, -14.20, -38.49

.270 Win. (150 grain @ 3000 FPS): +3.36, +4.36, 0.00, -10.25, -27.33

As the above tables clearly demonstrate, the 5.56mm NATO round is as suggested a "squib" and has precious little remaining energy beyond 200 yards compared with the other calibres, and I feel that this is a generous assessment. Its bullet drop characteristics are better than the projectiles of the 7.62 and .30-06, and it shoots flatter than both. But, lacking their knock-out punch, so what?

On the matter of accuracy with the 5.56 NATO round, I would dispel a myth that was rife in Vietnam. That being the projectile "tumbled" or rotated in an ellipse fashion along its axis. This assumption was made by many soldiers because of the damage the projectile could inflict at short range.

The reality is that any sharply pointed FMJ bullet may tumble if it hits something hard enough to destabilize or deform it, a large bone, for example. This tumbling effect has been noted by US troops ever since the adoption of the .30-06 cartridge and its 150 grain spitzer bullet in 1906. It is not unique to the 5.56mm bullet. But often a FMJ bullet will simply drill a bullet diameter hole straight through the target, particularly in soft tissue. The terminal performance of any FMJ spitzer bullet is unpredictable and any result other than a caliber diameter hole cannot be relied on.

Both the .30-06 round and the 7.62 x 51 round perform very well at all ranges out to 500 metres, with sufficient energy to stop most men in their tracks. I read some years ago that a rouge African Elephant was shot and killed at a range of approximately 100 metres with an FMJ 7.62mm NATO round. Before WW II many elephants and other heavy game were killed at fairly close range by .30-06, .303 British, and 8mm Mauser FMJ bullets.

Both the .30-06 and 7.62x51 are very accurate rounds, especially in bolt action or single shot rifles, as their target shooting records attest. There is also the indisputable fact that US snipers in Vietnam (and other theatres since) used the 7.62x51 round very effectively at long range.

I am reliably informed that, whilst the round was a 7.62x51, its similarity to that used in the GPMG M60 and the Australian L1A1 SLR ended there. Each sniper was responsible for handloading their own ammunition and, as their rifles were bolt action repeaters, it's quite possible that different projectiles and powders were used.

One shot kills have been recorded out to ranges of 1200 metres, and that is no mean feat.


I have personally experimented with my Omark single shot, heavy barrel target rifle, which has a Weaver 8 power scope fitted. Using 150 grain Sierra MatchKing HPBTs, IMR-4064 powder and magnum primers I have chronographed projectiles 15 feet from the muzzle at speeds averaging 2900 FPS. I have, on numerous occasions using that rifle and my hand loaded rounds, shot 6 inch groups or better at 800 metres.

If the Australian military and the US Senate are investigating the possible change to a bigger round for their GPMR and section LMGs, then the .30-06 and the 7.62 x 51 rounds should be high on their list.


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 Post subject: Re: 7.62x51mm NATO > Caliber Review

Master at Arms

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One shot kills at 1200m :shock:
I have seen it pierce steel plates from 600m but 1200m kill is amazing.


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 Post subject: Re: 7.62x51mm NATO > Caliber Review

Master at Arms

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Thanks for providing such detailed information about one of the most popular cartridges in the world, shooter bro :)

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 Post subject: Re: 7.62x51mm NATO > Caliber Review

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As I posted on the .308 thread, the following information is essentially incorrect:

Quote:
"The SAMMI/CIP maximum pressure for the .308 Win cartridge is 62,000 psi, while the 7.62x51 max is 50,000 psi. Also, the headspace is slightly different. The .308 Win "Go Gauge" is 1.630" vs. 1.635" for the 7.62x51. The .308's "No-Go" dimension is 1.634" vs. 1.6405" for a 7.62x51 "No Go" gauge. That said, it is normally fine to shoot quality 7.62x51 NATO ammo in a gun chambered for the .308 Winchester (though not all NATO ammo is identical). Clint McKee of Fulton Armory notes: "[N]obody makes 7.62mm (NATO) ammo that isn't to the .308 'headspace' dimension spec. So 7.62mm ammo fits nicely into .308 chambers, as a rule." You CAN encounter problems going the other way, however. A commercial .308 Win round can exceed the max rated pressure for the 7.62x51. So, you should avoid putting full-power .308 Win rounds into military surplus rifles that have been designed for 50,000 psi max."


The two rounds (.308 and 7.62 Nato) are the same round. The .308 was simply developed as the civilian version of the 7.62x51. The difference between the two psi ratings is that they were measured by different devices using different scales of measurement. If you do not reload, factory .308 and 7.62 is perfectly interchangeable.


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 Post subject: Re: 7.62x51mm NATO > Caliber Review

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Thanks for busting this internet myth JonnyC

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 Post subject: Re: 7.62x51mm NATO > Caliber Review

Marksman

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Please excuse my bumping this thread.

7.62x51 or 308 Win are available in a variety of grains:

Image

What is the preference of experienced shooters for target shooting at 300m to 500m?

What is the grainage of POF (Pakistani not Patriot) ammo?

What MOA can one expect to achieve from POF ammo?


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 Post subject: Re: Caliber Review > 7.62x51mm NATO

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I cant speek of the POF ammo and what is available.
But MOST .308 is loaded with a 148 or 150 grain bullet that gives excellent performance.
My friends and myself use the 168 gr Boat tail for long range target shooting, and some have had very good performance with the 190 gr at long distance.
For hunting I prefer a 180 grain bullet.
The 200 grain bullets IMO can not be driven fast enough in the .308 for good hunting performance over 300 yards.

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 Post subject: Re: Caliber Review > 7.62x51mm NATO

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POF 7.62x51 ammo has 150 grain FMJ steel core bullet and is berdan primed.

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 Post subject: Re: Caliber Review > 7.62x51mm NATO

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Useful info KBW, thanks.

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 Post subject: Re: Caliber Review > 7.62x51mm NATO

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150 gr .... hmmm :think:

So its lighter than even the lighter most bullet shown in pis posted by Zargham bro!!! :o

@ LAGS:
You mantioned "Boat Tailed" bullets in your post above. Which bullets in the pic posted by Zargham are "Boat Tailed"? (If any)

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 Post subject: Re: Caliber Review > 7.62x51mm NATO

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All of the bullets pictured are BOAT TAILED
A BOAT TAIL has a taper on the base of the bullet , rather than a base the same size as the bore or maximum diameter.

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Thanks LAGS! ;)

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 Post subject: Re: Caliber Review > 7.62x51mm NATO

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The weight of the bullet is not the only deciding factor; shape of the bullet also makes lot of difference. Two bullets of same weight but different shape can perform quite differently, specially at longer ranges.

POF 7.62x51 bullet has a long ogive, very pointed nose and longer boat tail. Due to this, the shank area that comes in contact with the bore has been reduced which results in mediocre accuracy. That is why, I would rate POF ammo as a very reliable ammo which has mediocre accuracy potential. In think reducing the size of boat tail and making the bullet less pointed (taking the ogive a little forward) will enhance the accuracy of POF ammo. They say that size of shank should be 1.5 times the caliber, ie, for 308 it should be .462 ". That means to provide more stability to the bullet, the area of bullet that comes in contact with the bore (lands) should be min .462" in length. In case of POF bullet, it is less. But I will request Ghazi sahib or LAGS to explain this technical thing in detail.

MR, all bullets shown in the pic have a boat tail, though of varying sizes. BTW, it is due to the steel core in POF bullet that it has less weight though the size is almost same as 168 grain bullet. :)

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KBW sir, thanks for such a detailed answer, and making us all wise on the subject!

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 Post subject: Re: Caliber Review > 7.62x51mm NATO

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KBW
you have already spelled the essentials. If a projectile or bullet does not have a shank ( the parallel sides of the bullet body which come in contact with the rifling) of 1.5 times its caliber the bullet is likely to have an IN BORE YAW this would result in in-accuracy at short to medium ranges and the bullets will KEY HOLE or would be TIPPERS
which means the bullets will hit with their sides and lose range and accuracy drastically at ranges of 200 yards and more.
This is specially true when firing machine guns with high rate of fire as the bullets would be practically going hay wire after three hundred yards when the barrels heat up and expand and the already short shank will barely stabilise the bullets.


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Nicely explained Sir. Thanks for the input. :)

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 Post subject: Re: Caliber Review > 7.62x51mm NATO

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Thanks Ghazi & KBW Sb. Learned something new today.
I don't know much about accuracy of POF bullets but once I was able to put 5 rounds in a 8 to 10 inch chest circle of a silhouette target from 300m using iron sights. That is good enough for me :) Of course not good for precision shooters.


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 Post subject: Re: Caliber Review > 7.62x51mm NATO

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Shariq wrote:
I don't know much about accuracy of POF bullets but once I was able to put 5 rounds in a 8 to 10 inch chest circle of a silhouette target from 300m using iron sights.

This is a guaranteed medal performance at national level. Not many in Pakistan would be able to make a 8" group with POF ammo from 300 M.

I think you need to do rifle shooting more regularly bro. This is a very good standard. :)

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 Post subject: Re: Caliber Review > 7.62x51mm NATO

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KBW wrote:
Shariq wrote:
I don't know much about accuracy of POF bullets but once I was able to put 5 rounds in a 8 to 10 inch chest circle of a silhouette target from 300m using iron sights.

This is a guaranteed medal performance at national level. Not many in Pakistan would be able to make a 8" group with POF ammo from 300 M.

I think you need to do rifle shooting more regularly bro. This is a very good standard. :)


Please do read that I mentioned ( Once ) in the sentence :)
I was not able to repeat it but I am able to shoot all 5 bullets on the silhouette target quite consistently. I think this sort of accuracy from military ammo is quite satisfactory.


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Thanks Ghazi Sir!

At last my question of "Beaten Zone" of MG has been answered with some science and logic!!! :D

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Machine Gun BEATEN ZONE
The beaten zone is a different thing all to gather. It is elliptical in shape and is formed because of the vibration causing dispersal of bullets. It is usually about 2m wide and 175 m long at the optimum machine gun range of 500 meters. At longer ranges it increases in width but shrinks in length. This is the kill zone of sustained bursts of machine gun fire when firing on a fixed line. All the bullets will be impacting in this area.
A machine guns fire is most effective when the longer axis of the beaten zone is parallel and over laps the longer axis of the target. ie a number of enemy soldiers coming in file engaged by the machine gun from the front or a number of enemy soldiers attacking in an extended line or wave and are engaged by a machine gun firing from a flank. This type of fire is known as ENFILADE fire and is devastatingly lethal as every burst will hit a very large number of enemy soldiers.
I think I am straying but since the word' Beaten Zone' was used I thought I may explain it.


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I would like to point out that Military Design ammo, ( Surplus ) is Made to be accurate.
But they also take in to account things that you will not be confronted with in most of your kind of shooting.
Like Very dirty barrels from repetive firing, Overheated barrels, and one ammo HAS To FIT Every gun in there arsinal.
For the riggors that a military round has to compinsate for in its design, I think they did a very good job in there universal design requirements.

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 Post subject: Re: Caliber Review > 7.62x51mm NATO

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Thanks for enlightening us Ghazi Sb.


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Once again, thanks a bunch Ghazi Sir for your such informative post! :D

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