does that mean that it sees service in .250 sav, or just that the prototype was in .250 sav?
WI: M1 Garand designed around .250-3000 cartridge
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SwampTiger
Banned
Let me try some of the questions in the original post:
1: Weight 9 lbs, Barrel length same, OAL 43 inches. I can't see a lightweight, select fire Garand from this POD.
2: Same as OTL, it is still the issue weapon
3: Possible BAR variant, US Army will not willingly start issuing select fire Garands without pressure from outside Ordnance.
4: M1 Carbine role remains, will be issued
5: All combatants will attempt develop a similar weapon during the war. Japan copied the Garand. Italy had several attempts at semi- auto rifles pre-war. They adopted one, Armaguerra 1939 in 7.35X51, but few entered service. The Breda PG was available, but not adopted. Germany and USSR had programs ongoing and rifles built. The UK may develop one. But probably not.
6: Post war development will start with smaller caliber cartridges. I foresee smaller cartridge cases and smaller rifles designed for full auto. The BAR is replaced by a true LMG/GPMG in the new caliber. I do not foresee the run to .22 caliber weapons. You may see true General Purpose Cartridge weapons replacing the full caliber rifles and machine guns, as well as the Submachine guns. The issue will be what will the Medium/Heavy Machine Guns use.
1: Weight 9 lbs, Barrel length same, OAL 43 inches. I can't see a lightweight, select fire Garand from this POD.
2: Same as OTL, it is still the issue weapon
3: Possible BAR variant, US Army will not willingly start issuing select fire Garands without pressure from outside Ordnance.
4: M1 Carbine role remains, will be issued
5: All combatants will attempt develop a similar weapon during the war. Japan copied the Garand. Italy had several attempts at semi- auto rifles pre-war. They adopted one, Armaguerra 1939 in 7.35X51, but few entered service. The Breda PG was available, but not adopted. Germany and USSR had programs ongoing and rifles built. The UK may develop one. But probably not.
6: Post war development will start with smaller caliber cartridges. I foresee smaller cartridge cases and smaller rifles designed for full auto. The BAR is replaced by a true LMG/GPMG in the new caliber. I do not foresee the run to .22 caliber weapons. You may see true General Purpose Cartridge weapons replacing the full caliber rifles and machine guns, as well as the Submachine guns. The issue will be what will the Medium/Heavy Machine Guns use.
I put these two quotes together because I will address both simultaneously (as well as a few other comments/questions regarding the development of alternate rounds for the AR platform and why they have been developed).
First, regarding the 'dissatisfaction' I have mentioned for the 5.56, I am basing that on reports and comments made by users in the field. Admittedly, some of it was second and third hand, but also some from direct first-hand experience that veterans have shared with me which back up some of the reports of the 5.56 simply 'punching holes' in enemy combatants rather than stopping them.
My talk of CQB was less about the ranges involved than about the weapons in use, short (10"-12") barreled sub-carbines--sorry I wasn't more clear on that. The 5.56 in a short-barrel CQB weapon does not achieve sufficient velocity for reliable fragmentation. Although the newest bullets have helped that I think there is a growing realization that a bullet which can stop a threat without having to rely on specific conditions to cause fragmentation is far more dependable than one that can only stop the threat with a perfect hit. The 6.8 SPC was developed specifically for this reason--it was not intended to be a long-range round for Afghanistan, but for clearing buildings room-by-room and to ensure that any hit on target would stop the threat, full stop. Its long range benefit, certainly important and recognized early on, was incidental to its development rather than intrinsic to it.
Here is a pretty extensive look at the development of the 6.8 SPC.
Additionally, the requirement for the 5.56 to fragment in order to reliably stop a threat is exactly why it struggles with armor. It is simple physics, really: if velocity is sufficient to fragment immediately on impact (which, you have pointed out, is what makes it so potentially deadly) then the energy is entirely expended and wasted as soon as it impacts the armor; conversely, if the bullet doesn't fragment then it is likely going too slow to carry the energy required to defeat the armor. The 5.56 can be built to do one, or other. It can either punch little holes, which will allow it to defeat armor, or it can fragment on impact which is easily defeated by armor. A round which fragments some time after impact may be able to defeat armor and cause sufficient damage to stop a threat but then it will have an issue with over-penetration on un-armored targets where the fragmentation doesn't begin until the round has already passed through the body (which has happened).
I don't know that I would characterize the new, forthcoming, 6.8mm as a 'magnum.' In fact, quite the opposite. What little information is available (nothing other than its targeted capabilities and caliber has been publicly released as yet that I have seen) points to it being of similar OAL as the 5.56 for compatibility with existing weapons platforms, likely of of a telescoping or even a caseless design. It will be intended as a full 5.56 replacement at all ranges. Considering it is being developed to stop all threats, armored and unarmored, I would also expect it to be non-frangible/non-fragmenting unless they decide to really complicate it and have a fragmenting jacket with a tungsten (or similar) perpetrator in the core--which I think would be too expensive for general issue in the order of tens of millions of rounds.
This is the gist of what I was trying to say previously. That with an established mid-caliber rifle cartridge already in use, I don't believe there would be sufficient benefit in adopting the 5.56 outside of very specific and limited roles.
This is a great point. The .250 can achieve better overall performance, at all combat ranges, than the 5.56 using lower chamber pressures. Adopting it to modern arms allows increased pressures for better down-range performance if such is desired and the .25 caliber family allows a wider variety of bullet options for development as well. It is simply a more versatile round than the 5.56.
Apart from recoil and weight benefit of the 5.56 I do not see any benefits to the round over our ATL improved 6.35x48 (.250 Savage) and I think we are at risk of overstating the benefits of the recoil. With the exception of laying down suppressing fire modern battle rifles are rarely every used in fully automatic. This role is much better suited to SAW/LMG weapons than the infantry rifle regardless of caliber. A friend who served in Korea in the late 90's and was involved in several engagements in the DMZ relayed to me afterward that he never fired his weapon in anything other than semi-automatic after training. For such uses the .250 Savage is still sufficiently light in recoil being roughly the equal of the 6.8 SPC (demonstrated to be sufficiently controllable in full-auto bursts) and close to the 7.62x39 AK as well. Again, the new 6.8mm round being developed is still unknown but I would think it, too, will be in the same recoil range. We are still talking about less than 1/2 the recoil of the 7.62x51mm, which in the M60/M240 is plenty controllable for full-auto support fire.
Deleted member 1487
The original 1915 .250 Savage probably was, but it had much worse range performance because to get that same sort of recoil requires using the 87 grain bullet and 1915 era powders.
Any idea how much heavier the cartridge was than the 5.56? Only being able to carry one for every two of 5.56 is a bit of an issue.
No, they settled on the .22 because it could achieve what they wanted from a SCHV round, while the bigger calibers could not.
Later when spec for the 5.56 cartridge that would be adopted was issued the .223 caliber was selected because it had already been proven the best for the concept in earlier experiments, they were just focusing on turning it into a military round.
Was that with the M855 round? Those reports are many and linked to the 'fleet yaw' problem, which the M855A1 was developed to fix. That said the military does train for shot placement as being most important to inflicting disabling wounds.
The M4 has a 14.5 inch barrel and the M855A1 cartridge is tailored to have the powder burn off before the end of the shortened barrel for max velocity, hence the rise in pressure. Even without the 855A1 construction being designed to fragment the M855A1 round does reach muzzle velocities to fragment at CBQ ranges (i.e. within 100m). That fragmentation velocity range is shorter than the full length M16 though, but the bullet design of the 855A1 is meant to remove velocity from fragmentation.
https://www.thefirearmblog.com/blog/2015/04/04/not-so-special-a-critical-view-of-the-6-8mm-spc/
The problem there is the potential for overpenetration, which removes a lot of the so-called 'knock down power' of the round by taking the majority of it's energy through a target, rather than tumbling and stopping inside the target.
The M855A1 proved otherwise, it can both fragment and penetrate. It isn't perfect of course, but that is also the issue with bigger heavier bullets, they will overpenetrate and do remarkably little damage if they aren't say hitting a load bearing structure or organ. You can find all sorts of videos on youtube of people doing damage tests with 7.62x39 vs. 5.56 rounds and being underwhelmed by the damage the bigger bullet does because it overpenetrates and just pokes holes. That is why Dr. Fackler's wound ballistics model emphasizes crushed tissue rather than temporary stretch cavity as being more important to incapacitation and death.
They talk about it being a high powered version unrelated to the SPC, so in that sense it is 'magnum'. I don't mean it in the sense of a true magnum, which is why I put it in quotes. Since the EPR design as been applied to the 7.62 in the M80a1 design I don't see why the military wouldn't want to use it for the new 6.8mm that is expected to be a 600m round. It can penetrate and fragment for better wounded ability. If you look up the Wound Channel on youtube they have all sorts of testing of the M80A1 and M855A1 in gel and against armor (and combined tests to see wounding ability beyond the armor effect). They even test different velocities too and against cover like brick.
That's the thing, the 6.35 is still considerably heavier per cartridge and more powerful in terms of recoil to the point that even the weaker version tested in the 1950s-60s pushed to over 1000m/s was decidedly inferior to the 5.56 and not adopted. The .250 Savage is something that is large enough in case capacity to be a 7.62 replacement before being a 5.56 one.
Whoa, based on what? That low chamber pressure 1915 version had worse trajectory and sectional density than the M193 5.56, not to mention worse muzzle velocity, while having more recoil and the cartridge being close to double with weight of a 5.56 NATO. If you soup up the .250 Savage then you have something more like the 7.62 in performance than the 5.56. More versatile sure (with caveats), but not specialized enough to outcompete the 5.56 in it's realm of expertise.
The recoil and weight benefits were incredibly important as was the muzzle velocity, which meant a controllable automatic burst, more rounds carried, and flatter trajectory which combined resulted in a lot more chance to actually hit a target within 300m. Doctrine on full auto use changed after Vietnam, but with all the work put into finding the future light rifle after WW2 and Korea based on combat experience they determined that infantry aiming error in combat was a big issue and burst fire with a light recoiling round was the only way to increase hit odds. Vietnam experience showed that it tended to waste ammo, but then they were not considering the impact of supressive fire and advantages that conferred...but there were instances of the infantry panicking and using up all their ammo on full auto. So at the time that the weapons are being developed in the 1950s-60s they aren't considering experience they did not yet have on the utility of automatic fire from infantry rifles, which lead to them thinking that the M14 could replace the BAR entirely. The SAW was developed as a result of Vietnam combat experience.
Again, I'm just talking about the reasoning that gave us the OTL 5.56 that wouldn't be any different here, especially given the potential realities of an upgraded 6.35 being made even more powerful. I think it would be a fine 7.62 replacement, but even the lower powered 6.35 tested IOTL was too powerful for an infantry rifle based on the doctrine/theories that were en vogue at the time. In modern times the upgraded .250 Savage would certainly be enough IMHO to fill the role of the modern proposed 6.8mm round that is being adopted, but the logic that lead to that wasn't around in the 1950s-60s when the .250 Savage upgrade would be around.
The thing is if the .250 Savage M14 doesn't run into the problems of the OTL model for whatever reason then you might be right that the 5.56 is never given a chance ITTL. That would of course, besides the design defects, rely on the build quality of the rifle to be better than IOTL and up to the rigors of the Southeast Asian environment. At the time none of the rifles the US military really were (other than WW2 surplus that was used in the Pacific) even the AR-15 or -10, as they weren't anticipating the next war being in a tropical climate. You might get lucky if the AR-10 in 6.35 was adopted, but given the politics around the M14 you probably will be stuck with that problem.
http://looserounds.com/2015/01/30/the-m14-not-much-for-fighting-a-case-against-the-m14-legend/
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if you guys are interested I can post the original military studies done that resulted in the 5.56 being developed and adopted so that you can see the reasoning that got them to the caliber in the first place and how the 6.35mm round wouldn't meet the criteria established at the time. Plus don't forget that the push after Vietnam was to adopt an even SMALLER caliber than 5.56; the British dropped their efforts to develop a 6.25mm round in the 1970s to work on a 4.85mm cartridge...and ended up right back at the 5.56 when all was said and done.
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I believe it was with the M855 round, yes. I readily concede that the M855A1 certainly improves matters I am trying to look at this from "TTL" point of view: if the 5.56 is adopted in the 60's as IOTL and there is dissatisfaction with the 5.56 similar to what was expressed after Vietnam and certainly later when the requirements were changing then why would all of that time and effort go into "fixing" an apparently flawed round (from TTL point of view) when it could instead be spent on improving one that already has (ITTL) the trust and affection of at least two generations of fighting men? We have already shown that even a "Full Power" infantry rifle version of the 6.35 with 120gr loads keep recoil at less than 10 pounds in a light (7.5 pound) rifle--it would be noticeably less in a 10 pound rifle--then wouldn't it make more sense to make a HV, light weight version for use in modern Assault-Style infantry rifles? Performance could likely duplicate the 6mm SAW, or nearly so, which I believe even you have put forward as a suitable alternative. This is why I have largely been by-passing references and performance of the post-2000's loads for the 5.56. My talk of the 6.8 SPC etc. has been more about the case that if the 5.56 is so intrinsically superior why are we still so actively looking at replacing it?
Not to say TTL 6.35mm is the end-all-be-all. As you've pointed out it is certainly flawed in several ways as a modern battle round. I just think that if a mid-caliber round were already established it would continue to be adapted and developed instead of replaced as the main infantry rifle round so quickly.
Which means a mid-caliber round with a slightly lower rate of fire may fare as well or better than a small caliber higher RoF round in direct comparisons of average infantryman's effective/practical accuracy.
Yes, but may operators and special police forces around the world are using 10"-12" barrels for increased maneuverability in vehicles and buildings. This is where the 5.56 really fails and is what initially inspired experiments to replace it with .30 and .277 caliber rounds for individual/custom load-outs. Admittedly, the military as a whole didn't start to look at the larger calibers until the need for long-range engagement became apparent.
A problem also shared by the 5.56 about 80% of the time prior to the M855A1. Again, not excusing the 6.35mm for it as I admit is a problem--but it is a problem for any non-expanding, high-velocity military round.
Again, the M855A1...see my comments above. Also, if we are so focused on requirements of fragmentation--why not develop a 80-100gr 6.35mm fragmentation round? Even the out-of-box factory loaded .250-3000 Savage can push a 100gr to 2900 fps (with on 7.8lbs of felt recoil in 7.5lb rifle). If you are looking for reliable fragmentation, Sectional Density becomes less important because you aren't gunning for all that much penetration. A 90gr fragmenting .25 caliber at 3000 fps should be able to meet any sub 400 yard requirement the Army may throw at it. But, as I've said, I don't like having to rely on fragmentation as it has proven to be something of a mixed bag.
Alright. Here is where it gets tricky. A .25 caliber round offers superior potential ballistics--in flight and terminal--to .22 caliber bullets. This continues until the best in-flight ballistics are hit at around .264 caliber (6.5mm) and best terminal ballistics are hit at about .284 caliber (7mm)--this is why there is such interest in .277 caliber (6.8mm) as it balances these two ballistic sweet-spots. The original .250-3000 Savage is a 1915 round and certainly no where near what modern .22 caliber rounds can achieve--the .223 Rem. is pretty much universally better than that original .250 Savage...but modern .25 caliber rounds have shown the potential of the caliber and with 100 years of development I have no doubt a military 6.35mm round could be made to reach that potential. Certainly, they may be heavier in mass and recoil than .22 caliber military rounds but they are still considered "friendly" to shoot (even such modern .25 calibers beasts like the .25-06 or .257 Wby. Mag), wonderfully reliable and accurate, and extremely versatile.
I'm not trying to say the 5.56 NATO is crap. Not at all. It is wonderful round that has served our combatants adequately and even sometimes admirably over the past 1/2 century and I personally really enjoy the .223 Rem. But it has limited development potential compared to 6-7mm rounds and IOTL has likely reached the limits of its usefulness as a primary infantry round. ITTL, I don't even know that it would survive long enough to see the level of development it has IOTL.
SwampTiger
Banned
If the US Army decided on a .25-.276 caliber round in 1929, we would not be discussing the .22/5.56 caliber in this thread. The .25 caliber and the others noted, can do nearly everything the .22/5.56 can do. Rifle development of the Garand, or whichever of the mid-1930's choices were competing, would have moved towards the Army's desire for a smaller 6.5-7 pound self loading rifle. Further development would be in the realm of select fire and automatic rifle variants. A carbine variant could have replaced the M1 Carbine. Lightweight plastics and materials technology would bring the weight down further.
Deleted member 1487
Again, no. An even lighter 6.35mm round was tested against the 5.56 round before it's formal adoption and the 6.35mm round was inferior. That was despite major sabotage the 5.56/AR-15 combo faced from the army testers. This is covered in detail in these books:
https://www.amazon.com/Black-Rifle-Retrospective-Modern-Military/dp/0889351155
https://www.amazon.com/Spiw-Deadliest-Weapon-That-Never/dp/0889350388
Now the .250 Savage modernized would have been superior to the 7.62x51 NATO round in direct fire roles, but the problem of the 6.35 is that is was simply too large to compete effectively in the SCHV role. This article covers why:
https://www.thefirearmblog.com/blog...ss-driven-design-field-small-arms-ammunition/
Deleted member 1487
I don't think that anybody was capable to respond in 2013 to a document made in 2017.
Deleted member 1487
That is the latest version of the article you linked, there are older versions. The link I posted though is more a direct response to Tony William's case for a general purpose cartridge, while the points that link makes also apply to the arguments put forth in the pdf you link.
Do they equally apply for 6mm, 6.35mm, 6.5mm and 6.8 mm that are discussed in Emeric Dainau's doc? Or perhaps on 6.5 mm neckless?
Deleted member 1487
Depends on the argument. Having glanced it over the argument is certainly there for replacing the 7.62 with nearly any of the range of 6mm calibers, but not a general purpose cartridge IMHO.
My point was that Nataniel F. analyzed 6.8mm cartridge proposed by T. Williams, but not the ranges of cartridges of 6, 6.35, 6.5 and 6.8mm proposed by Emeric D. who proposed 20 cartridges total, ranging from lightest variation of 6 mm to the heaviest variation of 6.8 mm. Plus the 'neckless' types.
2nd book is 290 US$ on.
SCHV demanded .22 calibre. The .25, being .25, cannot apply.
The '6.9 Romulan' != 6.35.
Deleted member 1487
You can find shared copies online or get it through interlibrary loan.
Yes, the 6.35mm is not small enough to qualify as a small caliber. It is on the lower end of medium.
The reality is you can push a smaller caliber faster with better aerodynamics than you can with a larger caliber. Which is why the 5.45mm Russian round is slower at the muzzle, but as similar or ballistics to the same weight of the original 5.56mm bullet out to 600m while having a lower recoil impulse. And it has a superior trajectory to the 7.62x39.
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Interesting perspective. I have to say, though, that the two approaches detailed in this article are only suitable for the first stage of development--the theoretical stage. I think that either solution presented would provide an adequate round but without real world application and direct comparisons it is hard to say which is actually the 'right' solution. Ultimately, these are simply hypotheses that need thorough testing in real-world environments.
Also interesting stuff. I haven't yet read it in detail but in previewing/skimming it I think the comparisons of 'Suppression'--though theoretical--are especially pertinent for our discussing but even more so the direct live-fire comparisons of different weapon systems beginning on pp.78 ('Impulse') which directly tests the entire concept of low-weight/low-recoil superiority. I like that we finally have tested data to look at instead of just theory and conjecture.
This is a very well thought out and put together opinion but I don't see how it can act as a response to the above without equivalent tests of the hypothesis that a GPC is inadequate.
Yes, indeed, thank you.
7.62x39, together with 7.92 Kurz and today's .300 Blackout, was an anti-thesis to ballistics.
The 5.45mm employed a long bullet with excellent BC, contrary to those 3 above.
When fired from same barrel length, the 5.45x39 is perhaps 5% slower than 5.56 M855.
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Deleted member 1487
There probably wouldn't be a need to 'fix' the 5.56 if the 6.35mm 'enhanced' round already has replaced the 7.62 in most direct fire DMR/sniper/LMG/MMG roles, as they already have a SAW type round specialized for medium to longer ranges. In time as the infantry rifle technology is upgraded and ACOGs are available en masse then likely the need for something like the 5.56 is not there are much. Still given it's advantages at 'short' ranges (0-400m) it probably won't go away especially for urban combat.
The big reason that the 5.56 M16 got the go IOTL was due to the M14 failing in so many ways and the AR-15/M16 being ready to step in to replace it, especially after special operations forces used it already to great effect and were asking for more. I agree that without the failure of the M14 it is unlikely that the 5.56 M16 would have gotten a chance to prove itself. However IOTL and for the same reasons ITTL since the M16 was already adopted by the Air Force and was in production already for military contracts, which the AR-10 was not (even in 6.35mm ITTL), it would get rushed into service for the Army as well. A special 'light' 6.35mm round would probably be something quite different from the .250 Savage, especially an upgraded version, as the 70 grain HV one was IOTL, so there is no real advantage to developing it from a production and logistics perspective, while at least the 5.56 has the advantage of being considerably cheaper per round.
Note that when I'm arguing this point, I'm not saying the 6.35mm round wouldn't have been fantastic and in many ways a round with as much potential as the 6mm SAW if not even more, just that the historical reasoning behind the 5.56 and the way it got into service as the primary rifle round for the US army was for a variety of reasons including what was quickly available on hand. Even the 6mm SAW wouldn't have gotten adopted with the reasoning used by the Defense Department IOTL in the 1960s (and wasn't in the 1970s IOTL).
The current situation with the 6.8mm cartridge is a function of maturing technology that opens up the range potential of such a cartridge to the average infantry soldier. The hard limit to about 300m for an infantry rifle was largely a function of how conscript infantry actually fought no matter the long range potential of the rifle they were issued due to any number of factors, but namely aiming and sighting errors by the troops. With a longer service, highly trained volunteer army and technology to fix aiming errors that is affordable and robust changes the game, especially with either telescoping or plastic case ammo reducing weight. Now, especially with the open ended commitment to Afghanistan and the use of body armor on the modern battlefield it actually makes sense to consider a rifle system with a larger caliber that can actually be used to engage and hit targets at longer ranges than was possible before. 21st century realities though aren't 20th century ones and there were limits on what was realistic in the field to be achieved with an infantry rifle, which drove decision making, which no longer really apply.
If there were another option quickly on hand to replace the flawed M14 then yes I'd agree with you, the problem was that of what was available in the US that was military grade approved the 5.56 M16 was really the only option and the only one that the McNamara DD wanted. I'm sure the FAL in 6.35 NATO would be available, but not produced in the US and not yet US DD approved, so it doesn't factor in to the decision. The AR-10 also had it's own storied history that prevented it from being considered at the time.
In the long run sure, but that took a while for the US to decide on after the failure of Project SALVO as well as plenty of combat experience and the transition to the all volunteer army in the 1980s. So likely when the US military is ready to reconsider calibers down the road the 6.35 would get the nod.
With those sorts of barrel lengths they're also using suppressors too, which means larger caliber subsonic bullets for which the 6.35 is also not really suited. Plus they are also considering convertable weapons so they can switch calibers on the same rifle quickly to meet different operational situations. That's an entirely different and specialized situation that goes far afield from what the US military would pick for general issue.
Not really given that it fragments at close range and it's best penetration is at 200m. The 6.35 would have the potential to be much worse for that. The M193 5.56 would break up completely at close range even on very limited cover, while the M855A1 would as well. IIRC even the M855 at close range would fragment, it just had spotty fragmentation at about 200m with the velocity drop.
Because that round would be quite a bit heavier, with substantially greater recoil, be substantially heavier per unit, produce more 'report', which could be a problem especially in confined spaces (granted a problem with the 5.56 HV round anyway), and so on. The issue isn't fragmentation anymore, as just about any caliber could be designed to do so independent of velocity, it is all the other stuff about the cartridge that has to be considered. Whether or no you like it fragmentation is the most damaging possible wounding mechanism short of an exploding (and highly illegal) round. Not even rounds designed to tumble inflict nearly as much damage and still can overpenetrate.
Terminal performance is debatable unless we're talking about an EPR design for all rounds. At that point the difference between the 6.5 and 7mm are effectively nullified. The 6.8mm caliber as I understand it was the max possible size while still having bearable recoil that doesn't impact accuracy.
IMHO the 6.35mm Savage modernized would be a winner to replace the 7.62 in most if not all roles if a larger caliber like the .338 takes over the longer range stuff. Still apparently the US military decided the 6.8 is even better for what their current objectives are. A lot will have to do with how heavy the rifle is and what sort of recoil management aids they adopt. The problem is at shorter ranges despite the virtues of the caliber they can't really compete with the virtues of smaller calibers, including weight and recoil on automatic or short bursts.
Arguably, and I think it is something to seriously consider, a micro-caliber round can and potentially should replace the 5.56 for infantry weapons in urban environs where ranges are exceptionally short. With the EPR design a 4.5mm round has even more virtues for that sort of situation than even the 5.56. In modern times there is a reason to subdivide things even more and have specialist urban combat weapons in addition to open environment weapons where distance will matter, especially if they can have mixed teams to deal with urban situations where penetration and range matter.
I didn't think you were. The 5.56 NATO was a cartridge designed for a specific period with certain technical and training limitations that made it highly desirable, but things have changed in the 21st century and I agree that the 6.35 cartridge we're talking about would be a contender for modern weaponry. It could well make sense to retire the 5.56 for something even smaller to specialize for shorter range environs, while the 6-7mm caliber rounds are developed to handle situations like in Afghanistan or more open areas where distance matters (or at least penetration performance does). But since we were discussing the likely change that happen over the course of the 20th century, I'm just pointing out why things happened as they did and how even the 6.35mm caliber would probably get somewhat sidelined as a result of the M14, as the 7.62 did.