WI: 7.62x51mm never becomes NATO standard

Deleted member 1487

Odd thoughts:

Curious why folk advocate 6.8mm rounds as modern ideals and dismiss the .270/280 which are about the same size. Also curious how the older 6.5mm rounds are either characterised as too powerful (Swedish) or too weak (Italian/Japanese) when the differences in the cases are a length of 55mm down to 50mm all with older powders.
The Italian 6.5 wasn't too weak or used particularly old powders (in fact it was pretty damn innovative with it's triple base tube powder and initial use of progressive twist rifling) it's just that it used a very heavy round nosed bullet which was aerodynamically inefficient instead of using a lighter faster bullet. To some degree the Japanese 6.5 had the same issue, plus that of a relatively weak powder. The Swedish round used a LOT of powder and by 1941 a very well designed aerodynamic bullet, which was too powerful for a infantry rifle that would be used with automatic fire (though still less than that of the 7.62x51 NATO), but was ideal for bolt action weapons and MGs.

The 6.8/.270 round was workable for automatic fire from an infantry rifle, but less than ideal, while the .280 was a bit too much even in it's lowest power form, while clearly the high powered versions were missing the point in terms of the original point of the round.

The order of events is what do you want the bullet to do. Then what case etc. will make it do it and then what weapon will best fire it. In real life nations want it cheap. In Europe there is no NIH syndrome as long as you can manufacture it at home (excluding France) but there was, and is, a huge NIH syndrome in the USA.
In the case of the US I think that without it being said the motivation was to keep costs down due to the budget cuts and huge surpluses from WW2 left over. Keeping to the same caliber minimized the cost of conversion as they modernized the 7.62 round and all the US obstinacy in that regard was less about the performance of the round and more about cost. At least that is my gut feeling having read about the 7.62 NATO development and adoption over the British rounds. The 'not made here' part was that the 'foreigners' were making a new standard that would cost too much to implement versus shortening and modernizing the 7.62 round and largely make all the left overs from WW2 useless and forcing a major retooling of production equipment. That was the rationale the Germans used with developing the 7.92 Kurz; the Germans got that the round was less than ideal, but given their investments in production equipment with a certain barrel diameter, bullet width, and cartridge casing width it only made sense to utilize what they already had than try to retool and create a new caliber out of the blue; the Italians ran into that problem during the war as they were converting away from 6.5mm rifles and the Japanese who tried to do the same when they were dissatisfied with the 6.5mm round's cover penetration in jungle fighting. It turns out that is really expensive and difficult to pull off in war time. The 5.56mm round later on at least benefited from using the existing .22 diameter bullet, for which there existed substantial machine tools in the civilian sector already (being based on the .222 Remington cartridge introduced in 1950 for the civilian market).
 

Deleted member 1487

Having professional soldiers that serve longer and get much better shooting training also. this allows them to make better use of the more powerful rounds. It also lead to better decisions regarding when to use full auto or aimed single shots.
Its interesting to note that, for example, Portuguese "comandos" use both 7,62mm and 5,56 rifles and LMG in Portugal, but when deployed to Africa or Afghanistan they choose to use their trusted old G3 rifles and MG3 GPMG, both in 7,62x51.
Regarding the logistic issue of having more than one type of round, once logistics became a "motorized sport" that's not as complicate as it used to be. The US army suplied both 30.06 ans .30 carbine, as well as .45 for SMG to Infantry units without problems.
For a german rifle unit depending on a horse driven supply cart in Russia it might be more critical to be able to swap round with the LMG team in the next fox hole.
Afghanistan's environment requires long range rounds, which 5.56 NATO is not designed to be.
In terms of the German situation in Russia the vast majority of the tonnage was first hauled by train first and then mostly by truck with a limited portion by horse. If horse carts were used it was at the shortest, final leg of the journey especially after 1941. There was a book at analyzed the Barbarossa campaign by a guy name Askey who looked at the logistics of the effort and proved that the vast majority of the hauling capacity was by truck, as even the huge number of horses used could only haul a small fraction of the tonnage and only shorter distances more slowly. Fewer trucks can easily out haul larger numbers of horses. The issue that maintained the single caliber standard wasn't ammo swapping between MGs and rifles, but at the production centers who could gain economies of scale by producing one type of cartridge.
 
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Curious why folk advocate 6.8mm rounds as modern ideals and dismiss the .270/280 which are about the same size.

The 6.8/.270 round was workable for automatic fire from an infantry rifle, but less than ideal, while the .280 was a bit too much even in it's lowest power form, while clearly the high powered versions were missing the point in terms of the original point of the round.
What the man said. I don't know that anyone is dismissing the .270 British out of hand, just that to fill the "full power" requirement of the US policy makers at the time it could have benefited from a heavier bullet and charge. It certainly would not be as controllable under automatic fire in an infantry rifle as any theoretical short 6.5mm, 6mm, or eventual 5.56mm but it may have been able to appease US brass. Wiking is right about the .280, though, I think that regardless of how you cut it it would have ran into problems similar to the 7.62x51mm when attempting to use it in automatic from a shoulder-fired infantry rifle. Still, I am beginning to agree with Wiking that if they could have worked out a good 6.5mm in 1950 that would have been the way to go. The problem is that no one (that I'm aware of) was actually working on a short 6.5mm cartridge as a potential NATO standard at that time.
 
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Regarding the logistic issue of having more than one type of round, once logistics became a "motorized sport" that's not as complicate as it used to be. The US army suplied both 30.06 ans .30 carbine, as well as .45 for SMG to Infantry units without problems.
For a german rifle unit depending on a horse driven supply cart in Russia it might be more critical to be able to swap round with the LMG team in the next fox hole.

True, it's not an insurmountable problem and good logistics systems are as ever their own reward! But it is still an extra factor, and one where the fail state is potentially a big problem if it does occur. Also not everyone has the logistic infrastructure of the US (and it's not like the US logistics has never failed either). However as you point out it not like armies haven't operated in this way without grounding to a halt!
 

Deleted member 1487

What the man said. I don't know that anyone is dismissing the .270 British out of hand, just that to fill the "full power" requirement of the US policy makers at the time it could have benefited from a heavier bullet and charge. It certainly would not be as controllable under automatic fire in an infantry rifle as any theoretical short 6.5mm, 6mm, or eventual 5.56mm but it may have been able to appease US brass. Wiking is right about the .280, though, I think that regardless of how you cut it it would have ran into problems similar to the 7.62x51mm when attempting to use it in automatic from a shoulder-fired infantry rifle. Still, I am beginning to agree with Wiking that if they could have worked out a good 6.5mm in 1950 that would have been the way to go. The problem is that no one (that I'm aware of) was actually working on a short 6.5mm cartridge as a potential NATO standard at that time.
Not at that time. A German company, IWK, experimented with a 7.62 and 6.5mm intermediate round in the 1960s, but that went nowhere. The 6.5mm round would have been interesting as an intermediate round:
http://www.municion.org/6Mm/6_5x43IWK.htm
http://www.cartridgecollector.net/65-x-43-iwk
https://forum.cartridgecollectors.org/t/iwk-6-5x43mm-experimental/24303

It used an aerodynamic 108 grain bullet (probably with a steel core) with 27 grains of propellant behind it (about the same amount of propellant as the 5.56 NATO round).
I'd estimate it would have ~725-750 mps muzzle velocity and around 1600-1800 ft/lbs of energy.

Maybe something like this wildcat round 6.5x40:
http://www.sadefensejournal.com/wp/?p=2414

Actually pretty close to the performance the 6.8mm SPC
https://en.wikipedia.org/wiki/6.8mm_Remington_SPC
but with better aerodynamic shape and with it somewhat less recoil.
 
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I can certainly see the temptation to go with two rounds each tailored for the job each will do out of different weapons. But you also run into having to support two different rounds, and lose out on potential benefits like supporting a range of weapons in the same calibre. However as ever it's always trade off!.
.

Is that true though? – the US army at the platoon level had in 1945 - .45 for Pistol and SMG, .30 Carbine and .30 cal for the M1 Garand

In addition it might also have had .30 cal in belt if MMGs had been pushed down to Platoon

So 3 possibly effectively 4 calibres (if we are treating belted ammo seperately) that have to be supplied – being replaced with 2 - lets say .270 Enfield for the Rifles and LMG/SAW in stripper clips and then a .30 cal MMG round for the MMGs (and sniper rifles but probably out of scope much below Battalion level) as well as pistol ammo which will be minute relative to the rest of the stores

For the British it is slightly less at Platoon Generally 9mm or .45 for SMG (possibly both), maybe some .455 for revolvers and .303 for LMGs MMG and rifles but more at Division + as you have to include 7.92 mauser for the BESA on British AFVs, .30 cal and .50 cal for US vehicles - not to mention other ammo types from 2" Mortar to 25 pounder

So the logistics burden has hardly been impacted and we already have at least 3 different weapon types in a given platoon not including side arms.

So for the USA you are replacing the SMG, Carbine and Rifle with a single weapon - surely thats an improvement?

And if a heavier calibre bullet is used for the LMG/MMG and Belts are used then thats not going to be an increase and if anythign a decrease in the ammo logistical burden. No?
 
One of the important things to remember about 5.56 x 45mm is that it's a very narrow cartridge (9.6mm rim), which means you can get a lot more of them in a specific magazine size than 7.62 x 51mm (12mm), .280 British (12mm), 6.5 Grendel (11.2mm), or 7.62 x 39mm (11.4mm).
 
@wiking, that 6.5x40mm (and the German 6.5x43mm) fit the bill nicely. I'm wondering, though, if they would have had more luck c. 1950 (without the OAL constraints of the 5.56x45mm) in NATO with a little more length, permitting a little more power. Something like a 6.5x45mm. Or, again, my proposed 6.8x48mm. I think either would be a good "sell" to round out the needs as understood at the time. A lead core 120-130gr FMJBT spitzer with MV of about 2500-2600 fps should fit the bill nicely. That will produce recoil on par with the 7.62x39mm (less than half the 7.62x51mm and about 180% of the 5.56x45mm). If, like the 6.5x40mm, it uses the same .30 Remington parent case as the 6.8 SPC (certainly a possibility in 1950) it would have a 10.7mm base diameter (addressing @Not James Stockdale's point above). This theoretical 6.5x45mm round would, in just about every way, almost perfectly split the difference between the 5.56 and 7.62 NATO rounds of OTL with superior standard combat range performance vs. 5.56 and equaling the 7.62 down range. Infantrymen could carry more of these than of the 7.62x51mm (but not so many as they can 5.56x45mm).
 
@wiking, that 6.5x40mm (and the German 6.5x43mm) fit the bill nicely. I'm wondering, though, if they would have had more luck c. 1950 (without the OAL constraints of the 5.56x45mm) in NATO with a little more length, permitting a little more power. Something like a 6.5x45mm. Or, again, my proposed 6.8x48mm. I think either would be a good "sell" to round out the needs as understood at the time. A lead core 120-130gr FMJBT spitzer with MV of about 2500-2600 fps should fit the bill nicely. That will produce recoil on par with the 7.62x39mm (less than half the 7.62x51mm and about 180% of the 5.56x45mm). If, like the 6.5x40mm, it uses the same .30 Remington parent case as the 6.8 SPC (certainly a possibility in 1950) it would have a 10.7mm base diameter (addressing @Not James Stockdale's point above). This theoretical 6.5x45mm round would, in just about every way, almost perfectly split the difference between the 5.56 and 7.62 NATO rounds of OTL with superior standard combat range performance vs. 5.56 and equaling the 7.62 down range. Infantrymen could carry more of these than of the 7.62x51mm (but not so many as they can 5.56x45mm).
The 6mm SAW cartridge that Frankford Arsenal was working on in the 1970s is very similar to what you specified. The brass-cased form is a 45 mm long case firing a .243" bullet of 105 gr at about 2500 fps. It had a rim diameter of 10.4 mm, so it would be smaller but longer than anything based on .30 Remington.

Overall, the problem with using an intermediate round to replace 7.62 x 51 mm NATO in machine gun and marksman applications is that 7.62 (150 gr at 2700 fps) is the smallest you would want to go for those kinds of roles. I have come to the conclusion (along with a lot of other people), that the gap between 5.56 and 7.62 cannot be adequately bridged, so any effort should focus on optimizing cartridges for the infantry rifle/SAW role and the GPMG/marksman role. I am personally partial to a mix of 6mm SAW (~95 gr at 2700 fps) and .338-06 (~200 gr at 2700 fps).
 

Deleted member 1487

@wiking, that 6.5x40mm (and the German 6.5x43mm) fit the bill nicely. I'm wondering, though, if they would have had more luck c. 1950 (without the OAL constraints of the 5.56x45mm) in NATO with a little more length, permitting a little more power. Something like a 6.5x45mm. Or, again, my proposed 6.8x48mm. I think either would be a good "sell" to round out the needs as understood at the time. A lead core 120-130gr FMJBT spitzer with MV of about 2500-2600 fps should fit the bill nicely. That will produce recoil on par with the 7.62x39mm (less than half the 7.62x51mm and about 180% of the 5.56x45mm). If, like the 6.5x40mm, it uses the same .30 Remington parent case as the 6.8 SPC (certainly a possibility in 1950) it would have a 10.7mm base diameter (addressing @Not James Stockdale's point above). This theoretical 6.5x45mm round would, in just about every way, almost perfectly split the difference between the 5.56 and 7.62 NATO rounds of OTL with superior standard combat range performance vs. 5.56 and equaling the 7.62 down range. Infantrymen could carry more of these than of the 7.62x51mm (but not so many as they can 5.56x45mm).
The main constraint IMHO with the 7.62 NATO issue is that the US was primarily focused on cost with their new round adoption and the 'power' or range issue was a red herring to justify their cost saving measure. So the US was never going to change caliber and at best would perhaps have been brought into a 7.62 intermediate round in addition to their full powered 7.62 round. I say that because based on our discussion here there were FAR better choices for a '1000 meter' round if they were specifically interested in performance. Your example above is proof of that. So how do we get around the cost conscious (or rather fixated) US Army? Also we should really note too that the 7.62 NATO was also somewhat of a stop-gap while Project SALVO was underway:
https://en.wikipedia.org/wiki/Special_Purpose_Individual_Weapon

This was underway at the same time as the 7.62 NATO round was being developed, though started a few years later. So in effect by sticking with the 7.62 NATO they were anticipating the 'two caliber standard' once SALVO bore fruit and the 'intermediate' rounds were basically pointless given the flechette round that was supposed to replace them. I suppose you would need to somehow prevent the SPIW project to get traction for anything other than the 7.62 NATO round...
 
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Deleted member 1487

The 6mm SAW cartridge that Frankford Arsenal was working on in the 1970s is very similar to what you specified. The brass-cased form is a 45 mm long case firing a .243" bullet of 105 gr at about 2500 fps. It had a rim diameter of 10.4 mm, so it would be smaller but longer than anything based on .30 Remington.

Overall, the problem with using an intermediate round to replace 7.62 x 51 mm NATO in machine gun and marksman applications is that 7.62 (150 gr at 2700 fps) is the smallest you would want to go for those kinds of roles. I have come to the conclusion (along with a lot of other people), that the gap between 5.56 and 7.62 cannot be adequately bridged, so any effort should focus on optimizing cartridges for the infantry rifle/SAW role and the GPMG/marksman role. I am personally partial to a mix of 6mm SAW (~95 gr at 2700 fps) and .338-06 (~200 gr at 2700 fps).
:)
I know it is my favorite 'what if' round. The Soviets also had a somewhat similar 6mm round that was to replace their 7.62 full powered round and be a universal caliber like the 6mm Optimum proposed round by Stanley Crist.
http://modernfirearms.net/en/machineguns/russia-machineguns/unificirovannyj-6mm-eng/

I actually have to strongly disagree. Crist makes a VERY convincing case that the 6mm 'Optimum' round would outperform the 7.62 NATO round out to 1200m in MG AND Sniper roles. The 6mm Optimum wouldn't be an intermediate in the sense of a 7.62x39, rather it would be a full powered 6mm round with excellent ballistic form and sectional density, while having the weight and aerodynamics to deal with drift and very low recoil.

I think the .338 is a very specialized role for very long range sniping and machine gunning/material destruction, largely replacing the .50 cal. Otherwise a full powered 6mm round, perhaps a bit lighter than the 105 grain proposed round, could do everything within 1000m, though it would be overkill for an infantry rifle...that is if it only used iron sights. With the advent of universal optics it could well be the next generation infantry rifle round, though that would leave open room for something smaller for short ranged roles, like either the 5.56 Colt MARS or a subsonic .300 blackout kit that would replace all SMGs, most if not all infantry carbines, and the vast majority of pistols in service.
 
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BigBlueBox

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The main constraint IMHO with the 7.62 NATO issue is that the US was primarily focused on cost with their new round adoption and the 'power' or range issue was a red herring to justify their cost saving measure. So the US was never going to change caliber and at best would perhaps have been brought into a 7.62 intermediate round in addition to their full powered 7.62 round.
Are you saying that we might have adopted 7.62x39mm or something very similar to it? Oh the irony.
 
I actually have to strongly disagree. Crist makes a VERY convincing case that the 6mm 'Optimum' round would outperform the 7.62 NATO round out to 1200m in MG AND Sniper roles. The 6mm Optimum wouldn't be an intermediate in the sense of a 7.62x39, rather it would be a full powered 6mm round with excellent ballistic form and sectional density, while having the weight and aerodynamics to deal with drift and very low recoil.

How much of an energy deficit would 6mm Optimum be at in the 300 - 600 meter range compared to 7.62 x 51 mm NATO? I don't doubt that a 6.5 (or so) mm full-size rifle cartridge would be superior to 7.62 NATO at extreme ranges, but effectiveness at shorter ranges should still be considered when you're looking at an overall smaller cartridge. that is trying to compensate via long-range ballistics. The 6mm SAW cartridge has about 80% of the muzzle energy of the 6mm Optimum, though I would increase the muzzle velocity and decrease the bullet weight to increase the zero-holdover range for infantry combat. The main point that drew me towards 6mm SAW was the increased effectiveness relative to 5.56 x 45 mm NATO in the 600 - 800 meter range, useful for SAWs and any infantry rifles with magnified optics. Personally, I think the future of infantry optics is in red dot sights with optional magnifiers (either fold to the side or just detach entirely while preserving the RDS's zero), so engagements at that range will be more viable.

I think the .338 is a very specialized role for very long range sniping and machine gunning/material destruction, largely replacing the .50 cal.

I'm not talking about a full power 8.6mm magnum cartridge like .338 Lapua (8.6 x 69 mm, 300 gr at 2700 fps). The .338-06 cartridge is just a .30-06 necked up for .338 bullets. The case capacity is about the same, but the larger bullet diameter allows you to use heavier bullets (200 - 225 grain) enabled by more advanced powders than those that were in use when the .30-06 cartridge was developed. I don't know how the ballistics of .308 and .338 bullets of the same weight vary, so it's entirely possible that these guns could use heavy loadings of .30-06 instead.

though that would leave open room for something smaller for short ranged roles, like either the 5.56 Colt MARS or a subsonic .300 blackout kit that would replace all SMGs, most if not all infantry carbines, and the vast majority of pistols in service.

My problem with the whole PDWs-replacing-handguns concept is that PDWs or SMGs are harder to carry and store than handguns. Someone who's sitting at a desk in the FOB all day can have their handgun on them at all times, while a PDW (even a small one like the MP7) is much larger and more difficult to deal with. Although there probably is space for an SMG-type weapon in very specific roles (suppressed, super-CQB), it's generally hard for the weight savings (going from a 10 lbs for a rifle and 3 mags to about 7 lbs with a larger PDW) to justify the loss in performance. I know there's also interest in vehicle and aircraft crews using PDWs in case they have to dismount (DEATH BEFORE DISMOUNT!), but a short-barrel, folding-stock rifle isn't going to be much bigger. Personally, I would assign much of the interest in this to the fact that the design of the AR-15 platform has prevented the implementation of a viable folding stock.
 

Deleted member 1487

Are you saying that we might have adopted 7.62x39mm or something very similar to it? Oh the irony.
No, just that that might have been the only, very unlikely, option due to the cost of caliber switching.

How much of an energy deficit would 6mm Optimum be at in the 300 - 600 meter range compared to 7.62 x 51 mm NATO? I don't doubt that a 6.5 (or so) mm full-size rifle cartridge would be superior to 7.62 NATO at extreme ranges, but effectiveness at shorter ranges should still be considered when you're looking at an overall smaller cartridge. that is trying to compensate via long-range ballistics. The 6mm SAW cartridge has about 80% of the muzzle energy of the 6mm Optimum, though I would increase the muzzle velocity and decrease the bullet weight to increase the zero-holdover range for infantry combat. The main point that drew me towards 6mm SAW was the increased effectiveness relative to 5.56 x 45 mm NATO in the 600 - 800 meter range, useful for SAWs and any infantry rifles with magnified optics. Personally, I think the future of infantry optics is in red dot sights with optional magnifiers (either fold to the side or just detach entirely while preserving the RDS's zero), so engagements at that range will be more viable.
Not sure to be honest, like the round would tumble when it hit a target at that range given the performance of the similar 6mm Lee Navy.
https://en.wikipedia.org/wiki/6mm_Lee_Navy#History_and_development
At the muzzle the M80 bullet of the 7.62 NATO would have had about 700 more ft/lbs of energy, which would bleed of much more quickly than that of the long, refined 6mm bullet of the SAW round.
Here is the Crist article in the Infantry Journal from 1999:
http://www.benning.army.mil/infantry/magazine/issues/1999/SEP-DEC/pdfs/SEP-DEC99.pdf
Penetration would be better for the 6mm round due to better sectional density than the 7.62 one:
https://www.chuckhawks.com/sd.htm

I agree with you that lowering the weight to about 95 grains and increasing the speed, perhaps utilizing a muzzle brake to reduce recoil, would yield very good results relative to the heavier round fired slower.


I'm not talking about a full power 8.6mm magnum cartridge like .338 Lapua (8.6 x 69 mm, 300 gr at 2700 fps). The .338-06 cartridge is just a .30-06 necked up for .338 bullets. The case capacity is about the same, but the larger bullet diameter allows you to use heavier bullets (200 - 225 grain) enabled by more advanced powders than those that were in use when the .30-06 cartridge was developed. I don't know how the ballistics of .308 and .338 bullets of the same weight vary, so it's entirely possible that these guns could use heavy loadings of .30-06 instead.
So...why use them? They would just be really heavy, slow bullets and lose the range benefits they'd have, which is the entire reason they have even been developed for the extreme ranges in Afghanistan.

My problem with the whole PDWs-replacing-handguns concept is that PDWs or SMGs are harder to carry and store than handguns. Someone who's sitting at a desk in the FOB all day can have their handgun on them at all times, while a PDW (even a small one like the MP7) is much larger and more difficult to deal with. Although there probably is space for an SMG-type weapon in very specific roles (suppressed, super-CQB), it's generally hard for the weight savings (going from a 10 lbs for a rifle and 3 mags to about 7 lbs with a larger PDW) to justify the loss in performance. I know there's also interest in vehicle and aircraft crews using PDWs in case they have to dismount (DEATH BEFORE DISMOUNT!), but a short-barrel, folding-stock rifle isn't going to be much bigger. Personally, I would assign much of the interest in this to the fact that the design of the AR-15 platform has prevented the implementation of a viable folding stock.
I get what you're saying...but the M1 Carbine didn't seem to cause people much trouble. Literal desk jockies wouldn't really even need handguns and if they really needed a weapon could go grab one off a rack nearby, as they'd much more likely than not have a lot of advanced warning that they'd need to defend themselves.
Have you checked out the size/capabilities of the Colt MARS? It was lethal out to 300m and used a 10 inch barrel.
https://en.wikipedia.org/wiki/Colt_MARS
http://municion.org/223/5_56x30ColtMars.htm
http://www.abovetopsecret.com/forum/thread20213/pg1
http://www.cartridgecollector.net/556-x-30-colt-mars-xpl

It uses a specially designed round with modern powder to get the most of the shortest barrel possible and still could use a folding stock.
 
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So how do we get around the cost conscious (or rather fixated) US Army?
The only way around this that comes to mind would be look at long term costs and sustainability--two things I doubt the US was concerned with, or even considering, at the time. There are few items that could be considered in any proposal to improve the argument for a 6.5mm-6.8mm Universal round from a cost standpoint.
  1. By making a multi-national agreement for shared tooling development some of the re-tooling costs could be mitigated and spread out through NATO.
  2. Consider the cost per round produced and spent
  3. Consider the material per round produced and spent
  4. Consider the cost per weapon purchased (lighter round allows for a theoretically lighter weapon with a potentially lower cost because...)
  5. Consider the material per weapon purchased (theoretically lighter weapon means less material per weapon)
Taken together, those itty-bitty savings accumulated per unit over Millions of units (ammunition) and hundreds of thousands of units (weapons) over a five year period (much less a 10 year period) could possibly represent sufficient enough savings to offset the cost of re-tooling for a smaller caliber. Remember, even with the adoption of the 7.62x51mm there was re-tooling cost so the difference between re-tooling for a smaller 7.62 (from the .30-06) vs. re-tooling for a 6.5mm will only be in actual bullet manufacturing--costs which are incurred each time a new variant is introduced regardless. We also cannot really consider the cost of introducing a new weapon to fire the new caliber because they were going to develop and introduce a new weapon regardless of the caliber. So, really, there are minimal to nil cost-savings with sticking to the 7.62mm vs adopting a new caliber.

The counter-argument to these potential savings per round of ammunition would, of course, be that the smaller round will likely be expended at a higher rate in new weapons systems. However, by designing the weapons systems for similar mechanical rates of fire the issue of infantrymen "spraying and praying" becomes a doctrinal and training issue not one related to any deficiencies with the new round. Naysayers (Ol' Mac, etc.) will try to counter that by saying it will require more hits on target to bring them down but, as we've already explored, at long ranges the theoretical 6.5mm or 6.8mm Universal round is the ballistic equivalent of the 7.62x51mm and still more than sufficient for one-shot incapacitation at standard combat ranges. Besides, neither of these arguments stopped the adoption of the 5.56 a decade later.

I am not saying these arguments would have or even could have worked but they are what comes to mind right now. Either way, we are back where we started on Page 1 where it is US hardheadedness that will hold it back c.1950.

I do think a 1950 adoption of a 6mm is likely pushing the bounds too far. As good as the 6mm SAW may be I do not see it being considered so early even if it had been developed. Like we said, even the 6.5mm may be pushing believably of the time with 6.8mm (.270) being more likely (being built up form the .270 British, or developed in the US from a shortened/necked down .276 Pedersen or likewise the .30 Remington). A modern adoption is another thing but even then I think 6.5mm-6.8mm is a better all-round choice.
 
I get what you're saying...but the M1 Carbine didn't seem to cause people much trouble.
I would point out here that the M1 carbine is longer than an M4 with the stock extended and weighs as much as a lightweight AR-15 build. A modern folding-stock assault rifle would end up being smaller than an M1 carbine, although it might weigh a pound more.
 

Deleted member 1487

The only way around this that comes to mind would be look at long term costs and sustainability--two things I doubt the US was concerned with, or even considering, at the time. There are few items that could be considered in any proposal to improve the argument for a 6.5mm-6.8mm Universal round from a cost standpoint.
  1. By making a multi-national agreement for shared tooling development some of the re-tooling costs could be mitigated and spread out through NATO.
  2. Consider the cost per round produced and spent
  3. Consider the material per round produced and spent
  4. Consider the cost per weapon purchased (lighter round allows for a theoretically lighter weapon with a potentially lower cost because...)
  5. Consider the material per weapon purchased (theoretically lighter weapon means less material per weapon)
Taken together, those itty-bitty savings accumulated per unit over Millions of units (ammunition) and hundreds of thousands of units (weapons) over a five year period (much less a 10 year period) could possibly represent sufficient enough savings to offset the cost of re-tooling for a smaller caliber. Remember, even with the adoption of the 7.62x51mm there was re-tooling cost so the difference between re-tooling for a smaller 7.62 (from the .30-06) vs. re-tooling for a 6.5mm will only be in actual bullet manufacturing--costs which are incurred each time a new variant is introduced regardless. We also cannot really consider the cost of introducing a new weapon to fire the new caliber because they were going to develop and introduce a new weapon regardless of the caliber. So, really, there are minimal to nil cost-savings with sticking to the 7.62mm vs adopting a new caliber.

The counter-argument to these potential savings per round of ammunition would, of course, be that the smaller round will likely be expended at a higher rate in new weapons systems. However, by designing the weapons systems for similar mechanical rates of fire the issue of infantrymen "spraying and praying" becomes a doctrinal and training issue not one related to any deficiencies with the new round. Naysayers (Ol' Mac, etc.) will try to counter that by saying it will require more hits on target to bring them down but, as we've already explored, at long ranges the theoretical 6.5mm or 6.8mm Universal round is the ballistic equivalent of the 7.62x51mm and still more than sufficient for one-shot incapacitation at standard combat ranges. Besides, neither of these arguments stopped the adoption of the 5.56 a decade later.

I am not saying these arguments would have or even could have worked but they are what comes to mind right now. Either way, we are back where we started on Page 1 where it is US hardheadedness that will hold it back c.1950.

I do think a 1950 adoption of a 6mm is likely pushing the bounds too far. As good as the 6mm SAW may be I do not see it being considered so early even if it had been developed. Like we said, even the 6.5mm may be pushing believably of the time with 6.8mm (.270) being more likely (being built up form the .270 British, or developed in the US from a shortened/necked down .276 Pedersen or likewise the .30 Remington). A modern adoption is another thing but even then I think 6.5mm-6.8mm is a better all-round choice.

I certainly agree with you that it makes more sense to consider things in the terms you're describing, but there was a LOT of WW2 stuff left over that could be harvested still by maintaining the 7.62 caliber standard; they were able to continue using WW2 stuff even into Vietnam after all. Plus there was the issue of the SPIW promising to cover the short range angle, so it seemingly made sense at the time to think that for the next 20-30 years at least it would make sense to maintain a large caliber round.

I wonder though if the US, even after moving to the 7.62 NATO, might not be willing to look at replacing it in the 1960s or 70s with something more efficient based on the experiences in Vietnam and serious calculations around the viability of the 6mm caliber as a universal round. That would maintain the 5.56 for infantry rifles, with the 6mm as a long range round, with the .50 for anything beyond that. Of course that is beyond the scope of what OP wanted, but that may well be the only non-ASB way to get the US establishment to eventually budge on the 7.62 caliber.
The Brits after all did try to replace the 7.62 again in the late 1960s with a 6.25mm round:
http://militarycartridges.nl/uk/6_25mm.htm
http://quarryhs.co.uk/256brit.htm
In the late 1960s, the Royal Small Arms Factory at Enfield began a detailed theoretical analysis of the striking energy needed to disable soldiers with various levels of protection, and the ballistics required to deliver that energy at battle ranges for a number of different calibres. The conclusion was that the optimum calibre would lie between 6mm and 6.5mm, and an experimental 6.25x43 cartridge (based on the abortive 7mm round) was developed which was claimed to have significant advantages over both the 5.56mm and 7.62mm calibres. Performance proved to be virtually equal to the 7.62mm at up to 600 metres, with recoil and ammunition weight much closer to those of the 5.56mm.
 
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Deleted member 1487

I would point out here that the M1 carbine is longer than an M4 with the stock extended and weighs as much as a lightweight AR-15 build. A modern folding-stock assault rifle would end up being smaller than an M1 carbine, although it might weigh a pound more.
The thinking, probably rightly, was that there was a significant chance of combat for ground forces in rear areas issued M1 Carbines, so the fixed stock was a boon rather than a draw back. Now there was the paratrooper model, which was quite a bit lighter and more compact.
AUTO%20ORDNACE%20M1%20PARA.gif


But for people in confined spaces like tanks, the M3 Grease gun was used. As that used an 8 inch barrel, it was about as compact as you can get for a PDW before the Uzi, but with only 50m accurate range. With a folding stock the Colt MARS did rival the Grease Gun in size and probably bettered it in weight with accuracy and leathality out to 300m.
 
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to get the most of the shortest barrel possible and still could use a folding stock.
Sig Rattler in 300 BLK
Sig.debuts.MCX_.Rattler.rifle_.and_.pistol.in_.300.BLK_.VIDEO_-1.jpg


Nothing that couldn't have been done in the late '50s. and 300blk is still accurate and develops good performance, like a weaker 30-30 or 7.62x39
5.7 pounds 16" long with stock collapsed.

yeah, it's bigger and heavier than an M9 pistol, but a lot easier to shoot and a far more effective cartridge.
 

Deleted member 1487

Sig Rattler in 300 BLK
Sig.debuts.MCX_.Rattler.rifle_.and_.pistol.in_.300.BLK_.VIDEO_-1.jpg


Nothing that couldn't have been done in the late '50s. and 300blk is still accurate and develops good performance, like a weaker 30-30 or 7.62x39
5.7 pounds 16" long with stock collapsed.

yeah, it's bigger and heavier than an M9 pistol, but a lot easier to shoot and a far more effective cartridge.
Perhaps propellants weren't up to modern standards in the 1950s?

My personal favorite though for subsonic suppress .300 blackout:
 
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