Why did the 7.62x51 cartridge come out of the WW2 era?

7.62x51 for all intents and purposes is a 30-06 short. From a story my father told me (WW II vet), the short round was developed around the desire for a shorter action and higher cyclic rate. Anecdotal story and no proof but seems reasonable to me.

.40

The shortened 30-06 round (7.62x51) did what was necessary and fed well in machine guns like the M-60.

With better slow burning powders the 06 was larger than neccessary. With NATO being formed they wanted ammo that would be universal for all NATO weapons from all countries.

The shortened 30-06 round (7.62x51) did what was necessary

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...by exactly duplicating military 30-06/ball ballistics in a shorter round/medium action amenable to a moderate-size removable magazine

Army Ordnance wanted to keep the performance of the .30-06 and with newer powders available after WWII the case capacity could be reduced. Shorter case = smaller, lighter rifle.

Army Ordnance then proceeded to cram 762 NATO down the throats of the Allies while burning the Brits by not adopting the FAL as the NATO standard rifle.

762NATO was adopted in spite of all the evidence that the best rifle caliber would be something intermediate in the 6.5 to 7mm caliber.

BSW

Easy. Because we won and they didn’t. Our military industrial complex could sell our stuff to non-winners

You need to understand that much military hardware isn’t necessarily to best. It simply has to be adequate, and manufacturer be affiliated with the correct politician. The disaster of the F-35 proves that.

Vietnam wasn’t about winning anything. It was about wasting as many resources as possible. If you don’t understand that, watch Hamburger Hill. We had to take that ground at any and all cost. We left three days after taking it.

Here’s a video that will give you some info on how the 7.62x51 became the NATO round.
https://www.google.com/url?sa=t&rct...=jexf8A462jM&usg=AOvVaw1dcxPmqxS2FV3Vuv3IQdIp

Funny but true story. My Dad was stationed in downtown London in the mid-1960's at US Army Group UK. He worked in civvie clothes in an office on Oxford Street. They were working with NATO standardization efforts, and the Brits had a night sight that they thought would work with the M14. Not having one in the office, Dad walked down the street to the US Embassy, and signed out one from the Marine contingent there. Not wanting to draw attention, he carried it at "trail arms" all the way back to his office. Much to his chagrin, in the hustle and bustle of the city crowd, it doesn't appear that anyone took notice of him.

The shorter dimensions made it more useful for detachable magazines for the new rifles coming out at the time in NATO (M14, G3, FAL) and it also worked well in the machineguns (M60, MG3, FN MAG). The 30 caliber meant that many accessories like cleaning rods would also work- so a rifleman or machine gunner in viet nam in 1973 could in theory use a US cleaning kit from well before WW1.

Has anyone ever noticed that a charged -06 case loaded with powders of the WWII era, such as IMR 4895, is only about 2/3 full? I think in that respect the 30-06 cartridge was poorly designed. The 7.62 x 51 case is appropriately sized for the powder charge needed to launch a 150 grain bullet. I don't think powders in the mid-range burn rates had been improved that much in the 1950's to make a big difference in the cartridges performance. 4895 is still an excellent choice in .308.

Now slower burn rate powders have made a difference in the -06 with heavier bullets due to the larger case capacity that can hold a bigger charge. But that was never the intent in 1903.

Laphroaig said:

Has anyone ever noticed that a charged -06 case loaded with powders of the WWII era, such as IMR 4895, is only about 2/3 full? I think in that respect the 30-06 cartridge was poorly designed. The 7.62 x 51 case is appropriately sized for the powder charge needed to launch a 150 grain bullet. I don't think powders in the mid-range burn rates had been improved that much in the 1950's to make a big difference in the cartridges performance. 4895 is still an excellent choice in .308

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They didn't design it around 4895 so you can't say it was poorly designed on this point, the .30-03 was designed to use the same old nitroglycerine powder as the Krag, and the .30-06 came from the .30-03. That explains why it is the size it is. They quickly moved to improved powders but they are still long obsolete, such as "Pyro DG": 50 grains, 150 gr bullet, nominal 2700 ft/sec from the Springfield. But according to Nosler even 50 grains of your IMR 4895 still has ~88% case fill with a 150 gr bullet.

Plenty of reasons. Big Army determined that most engagements happened in relatively short distance. I believe the official number was right around 500 meters. 30-06 was good and can shoot far. More general warfighting could be done at closer range with lighter firearms, lighter ammo, and soldiers could carry more gear. Sub guns like the Thompson, grease gun, etc were highly portable but were in weaker pistol cartridges. So a ballistic compromise was made, intermediate cartridges. Some of the common chamberings in this category today are 5.56, 7.62x39 etc.

There is always a push in the military to domestically source war goods. Vehicles, firearms, ammo, supplies etc. And Congress critters like to bring jobs to their districts, even from overseas businesses like FN, Beretta etc.

The Exile said:

During World War 2 there were a lot of high power rifle cartridges running around, Japanese 7.5, German 8mm, American 30-06, etc. but shortly after the war all of those were replaced (in NATO territory) by the new 7.62. Was something wrong with all these other cartridges that were probably in abundance like nobody's business that necessitated the adoption of a new round? Were some rounds knocked out for political reasons (IE not wanting to adopt the Nazi 8mm, because it was from an enemy nation)? The soviets for some reason insisted on sticking with an ancient rimmed cartridge well into and after the cold war so I can't even fairly discount the 303 on that basis.

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You know, books have been written around that question. The Army went into WW2 believing that long range, accurate rifle fire was the most important thing. This came from the 1919 Superior Board Report on Organization and Tactics. The US exited WW1, about 60% of the causalities, if not more were due to artillery, and yet the Superior Board claimed what the Army needed was more sharp shooting riflemen!

You know, the US hit a causality rate of 65,000 men per month in WW2, and by the time you get to 1943, (as reported in the American Rifleman) Infantry Officers were keeping their rifle men from shooting at the enemy at distances over 300 yards. The reason was, the shooters could not hit anything, and the enemy would respond with artillery fire and kill some people! It took years to teach marksmanship and those guys who could shoot straight were piles of rotted meat and busted bones around year two. Post war there was a lot of discussion whether long range accurate shooting had any value on a battlefield.

But, if you ever encounter the "User", you will find that they like what they have, want something better, but only a little different, and will reject revolutionary change. What the Infantry School wanted, was something that had the power of the 30-06, but weighed as much as an M1 Carbine.

The 30-06 was too long for a good automatic or semi automatic rifle round. That extra half inch in length adds un necessary length and size to the weapon. The rim was thin, so the 7.62 round is more compact, and has a thicker rim. It was recognized at the time, that is WW1, that the 30-06 was not optimal for the powders at the time of its creation. Now the 7.62 round,, the powders of the era gave the velocities, at the desired pressures, and filled the case. No wasted air space.

I like the 308 Win, I would have voted for it, it is accurate, powerful, and but, given that we are not going to train the military to high levels of marksmanship, the long range accuracy and power of the cartridge is wasted. One bud of mine, a Vietnam infantry solider, he liked the combat load of the M16, he could carry 400 rounds, instead of 200 7.62, and he had on bad days, fired all 400 rounds! His engagement distances were short. Yes the 7.62 would penetrate trees and bushes better, but you had to be on the receiving end to know that.

It’s a good question, and I’m sure almost all the reasons behind it are for logistical reasons. I’ve always liked the Swiss 7.5x55 GP11 cartridge. I think in some ways it’s superior to the 7.62x51, though very similar. I think it could have been a perfect NATO round, But even the Swiss switched over to 7.62x51. not for ballistics, but for logistics.

Alluded to but not specifically mentioned was the desire for cartridge cases better suited to fully automatic weapons. Which explains the thicker, stronger web in the 7.62mm version than in the .30 caliber version. Shortening the case by roughly half an inch made for lighter receivers as well. Not to mention that cyclic rate concept mentioned above. The caliber (bore diameter) for the 7.62mm is exactly the same (within tolerances) as the .30-06, the .30-03 and the .30 Army (.30-40 Krag). If anyone - other than me - conjures the idea of governmental economy in this arrangement, live with it.

Incidentally the official version developing the 7.62x51mm refers to the .300 Savage as the real inspiration. Since the .300 Savage uses the same shell head holder and the same diameter bullet, it is hard to differentiate between the .300 Savage and a 'shortened .30-06' case.

As stated, there was a non 308 cal attempt with the Garand. The main reason it wasn't adopted was logistic. With billions of rounds of 3006, it just made sense to stick with something that was already in the arsenal stores and not reinvent the wheel. That's why it took till the switch to the M16 to get to the 5.56 v the 7.62. Ballistically, the 276 Pedersen was a far superior cartridge to the 3006.

Jap was 7.7, not 7.5. I tried .308 in mine, keyholes. .312 cured that.

As an outsider, and having come along after the fact when you look at the whole 7.62 NATO development and forcing on the NATO members it seems to have gone like this: US armed forces decides they want a logistically superior, lighter round for a shorter, lighter rifle in order to overcome the perceived issue with the M1: weight and lack of firepower compared to the oncoming assault rifles. This movement was met head on by a head strong contingent who believed that the power of the 30-06 and diameter was perfectly suited and should be maintained. Hence the 7.62X51. Same diameter and power, and allowing a slightly shorter lighter rifle, with a little less recoil. However it was a FAIL in that it really was not a logistical improvement and could not be controlled in full auto effectively.

The Exile said:

During World War 2 there were a lot of high power rifle cartridges running around, Japanese 7.5, German 8mm, American 30-06, etc. but shortly after the war all of those were replaced (in NATO territory) by the new 7.62. Was something wrong with all these other cartridges that were probably in abundance like nobody's business that necessitated the adoption of a new round? Were some rounds knocked out for political reasons (IE not wanting to adopt the Nazi 8mm, because it was from an enemy nation)? The soviets for some reason insisted on sticking with an ancient rimmed cartridge well into and after the cold war so I can't even fairly discount the 303 on that basis.

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Why? Common logistics for NATO, as noted. The MG links are also standardized.

Why .30-06 short and not what the British were pushing? Armor piercing performance at medium range. The US in WW2 has used mostly AP as standard combat ammunition, even in rifles to good effect. With the Soviet threat of thousands of BTR-152s carrying the Soviet "hoards", the Army wanted ammunition that put a hole in one.

Oh, and by the way, most of Western Europe was without weapons after the war, and guess where they got them to rebuild their armies? That's right, the US.

JShirley said:

It's just one of the many great mistakes Doug MacArthur is responsible for

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Actually, that was one of the correct decisions made by him.

Look at the Army budget from 1935 to 1939. Look at the number of M1 produced during that period. What do you think the volume of .276 ammunition would be produced during this period? How many commercial concerns would have gained experience loading this new ammunition type? Or, even been tooled up for it?

If the M1 used different ammunition from the M1918 and M1919, ammunition produced on a smaller industrial base than Caliber .30, chances are the M1 would have been dropped as the standard service rifle in favor of the M1903.

Strategic level logistics, it's the same reason the British pressed on with the SMLE and .303 in WW1 rather than switch to the Pattern 13 in .276.

redneck2 said:

Easy. Because we won and they didn’t.

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In a nutshell this is the true answer.

Since the .300 Savage uses the same shell head holder and the same diameter bullet, it is hard to differentiate between the .300 Savage and a 'shortened .30-06' case.

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The 300 Savage, 308 and 30-06 all use the same shell holder. A 30-06 load during WW-1 had a 150 gr bullet at 2700 fps. The 300 Savage successfully matched that and when introduced would do the same thing as 30-06. By WW-2 a 150 gr 30-06 load was up to 2800 fps. I may be mistaken, but I believe that when WW-2 started that was the standard load. At some point a heavier bullet was designed for machine guns and eventually used in rifles too. But I'm not 100% sure I have that exactly right.

When the 308 was developed it was based on a modified 300 Savage case rather than a shortened 30-06 case. But even that is splitting hairs since the 300 Savage is still based on 30-06.

As a service rifle cartridge the 308 and the rifles designed for it was a failed experiment. Not that they aren't great rifles, but they just didn't meet the need the military was looking for. What they wanted was a smaller lighter rifle capable of holding a lot more ammo and still controllable in full auto fire. What they got was a redesigned Garand with a detachable magazine firing a cartridge nominally smaller, but with the same recoil.

The 308 has proven to be a great round and filled a niche as close to mid-range sniper round and as a light machine gun round. The M14 is still seeing limited uses in the military for specialized roles. But while the 5.56 has it's issues, I still maintain that as a general issue option we are better off with it than we would have been had we stayed with 308 or any of the larger cartridges.

jmr40 said:

But while the 5.56 has it's issues, I still maintain that as a general issue option we are better off with it than we would have been had we stayed with 308 or any of the larger cartridges.

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+1
The evolved Stoner/5.56 Combination has proven itself one of history's greatest/most flexible/longest-lived military small arms.

- Brown Bess (116 years)
- AK47 (72 years)
- M16/4 (56 years)