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The Case Against A General-Purpose Cartridge


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#1 BabyOlifant

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Posted 25 November 2013 - 0043 AM

Posted with respect to Mr. Williams.

 

I request that responses be kept civil and on-topic.



#2 rmgill

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Posted 25 November 2013 - 0221 AM

Wait, how is issuing a CGustav more cost effective with limited round count for those in a platoon than is a 6.8 GPC? Sure if you only have a few long range targets and don't run out of CG rounds.

And I thought line infantry were getting more rifle time and training for the longer ranged engagements that were happening.


Edited by rmgill, 25 November 2013 - 0223 AM.


#3 BabyOlifant

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Posted 25 November 2013 - 0236 AM

The CGs are replacements for mortars if it is determined that mortars do not fit well with new ROE. They are there only for comparative purposes.



#4 rmgill

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Posted 25 November 2013 - 1038 AM

But isn't this about extending range capability in fire fights?

#5 Sebastian Balos

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Posted 25 November 2013 - 1417 PM

Posted with respect to Mr. Williams.

 

I request that responses be kept civil and on-topic.

Who cares about ammo being more advanced or more mv, when you get ammo commonality and more stopping power than 5.56...

 

7.62x39 may be less "advanced" than 5.56, but under some circumstances, it may be more effective.

 

So, effectiveness is the key, not mv or just being advanced.

 

The recoil? 7.62x39 mm recoil is unacceptable? This is getting funny - I've fired it and it was literally funny. I0ve never fired 5.56, but judging from numbers, it is even funnier. Unfortunately, its stopping power from a short barrel and long range is funny as well. No, training is the key, as well as reflex sights (secondary), not selective fire and huge ammo loadouts.


Edited by Sebastian Balos, 25 November 2013 - 1427 PM.


#6 BabyOlifant

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Posted 25 November 2013 - 1611 PM

But isn't this about extending range capability in fire fights?

 

Many who qualify Army "expert" are unable to hit targets beyond 300m effectively, regardless of caliber. Maybe things are better in the USMC, I do not know, but I do not think the reason most riflemen are ineffective at long range has much at all to do with the caliber of weapon they're using. If we're strictly talking trajectory I can guarantee it, in fact, since I find 5.56mm to have much the same trajectory and pH as 7.62x51 out to 800m.


Edited by BabyOlifant, 25 November 2013 - 1611 PM.


#7 BabyOlifant

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Posted 25 November 2013 - 1614 PM

 

Posted with respect to Mr. Williams.

 

I request that responses be kept civil and on-topic.

Who cares about ammo being more advanced or more mv, when you get ammo commonality and more stopping power than 5.56...

 

7.62x39 may be less "advanced" than 5.56, but under some circumstances, it may be more effective.

 

So, effectiveness is the key, not mv or just being advanced.

 

The recoil? 7.62x39 mm recoil is unacceptable? This is getting funny - I've fired it and it was literally funny. I0ve never fired 5.56, but judging from numbers, it is even funnier. Unfortunately, its stopping power from a short barrel and long range is funny as well. No, training is the key, as well as reflex sights (secondary), not selective fire and huge ammo loadouts.

 

 

I do not know of any satisfactorily rigorous examination of terminal ballistics that would be necessary to make those kinds of assertions.


Edited by BabyOlifant, 25 November 2013 - 1646 PM.


#8 Sebastian Balos

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Posted 25 November 2013 - 1644 PM

You mean stopping power? Come on, there are numerous accounts on the insufficient stopping power of 5.56 if it's not fragmenting... Somalia with basically AP ammo that's not fragmenting and the application of short barrel that's not developing sufficient mv for fragmentation over 'say 50-100 m. 7.62x39 ammo is superior due to its higher diameter even if it doesn't fragment.



#9 BabyOlifant

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Posted 25 November 2013 - 1659 PM

You mean stopping power? Come on, there are numerous accounts on the insufficient stopping power of 5.56 if it's not fragmenting... Somalia with basically AP ammo that's not fragmenting and the application of short barrel that's not developing sufficient mv for fragmentation over 'say 50-100 m. 7.62x39 ammo is superior due to its higher diameter even if it doesn't fragment.

 

That doesn't really convince me.


Edited by BabyOlifant, 25 November 2013 - 1713 PM.


#10 Ivanhoe

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Posted 25 November 2013 - 2019 PM

A couple of weeks ago I read the assertion, maybe here, that complaints about the lack of terminal effectiveness of M855 dried up after optics became universally issued in some particular unit OCONUS.
 
----
 

A final note: Mr. Williams is primarily a writer and a theorist. While he has definitely fired a rifle before, he is not, to my knowledge, a habitual shooter, and has likely never shot for accuracy beyond a hundred meters. His intentions are good, but he does not have the experience to fully appreciate the difficulty of hitting a target with a rifle, even in calm conditions, at extended ranges. He thus perceives infantrymen armed with more powerful, longer-ranged rifles as having greater capability than those armed with 5.56mm carbines, when in fact, for the vast majority, the heavier cartridge and necessarily heavier rifles and magazines merely increase their burden. In short, giving long-range rifles to line infantrymen without additional training is a waste of strategic resources, money, and time. This is not to say that specialized marksmen would not be able to take advantage of such a cartridge, but they would be better served by a specialized rifle firing a cartridge with higher velocity and better hit probability at range, not the inherently compromising GPC.

 
Unless the author has access to HUMINT or continuous satellite coverage of England, targeting Tony specifically, the above claims are completely unsupported by data, and appear to me to be a rather juvenile attempt at ad hominem. And a reader might ask what experience the author has in hitting targets with rifles.
 
Also, it was trivial to find a non sequitur;
 

Is a 25% worse trajectory, increased bolt stress, lower reliability, fewer rounds per magazine, and the introduction of an entirely new cartridge worth a 10% increase in energy per kilogram at half a kilometer?

 
I didn't see any data on reliability presented. Now 6.8SPC may very well be less reliable than 5.56, but in this context citation of empirical data is kind of a tradition.

Oh wait, here's another one;

Beyond (valid) concerns about the cartridge's extreme shoulder angle and lack of case taper, the case itself does not have enough internal volume to accept tracer or steel-cored armor piercing projectiles, except with the lightest bullets. Thus, it cannot fulfill the role of a GPC, as it is not a suitable military cartridge.


Poorly explained, but apparently leveraging off the myth that you can't have bullet bases or boattails intruding into the case past the base of the neck. My suspicion is that old wives tale dates back to cast bullets, and particularly the development of gas checks. There's a classic photo of bullet intrusion in one of Ken Waters' Pet Loads articles, I believe for the 6.5mm Remington Magnum, in which those looong 140 grain 6.5mm bullets protrude far, far into the case. I've not seen one of those sectioned round pics for the newer 5.56 rounds, but I would imagine that some of the .223/5.56 loads using 77 grain match HPs and similar bullets have notable intrusion.

In summary, I think most of us could write a 10-20 page critique of the article while leaving a half-dozen or so booboos for the reader to eviscerate.

#11 BabyOlifant

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Posted 25 November 2013 - 2053 PM

A couple of weeks ago I read the assertion, maybe here, that complaints about the lack of terminal effectiveness of M855 dried up after optics became universally issued in some particular unit OCONUS.
 
----
 

A final note: Mr. Williams is primarily a writer and a theorist. While he has definitely fired a rifle before, he is not, to my knowledge, a habitual shooter, and has likely never shot for accuracy beyond a hundred meters. His intentions are good, but he does not have the experience to fully appreciate the difficulty of hitting a target with a rifle, even in calm conditions, at extended ranges. He thus perceives infantrymen armed with more powerful, longer-ranged rifles as having greater capability than those armed with 5.56mm carbines, when in fact, for the vast majority, the heavier cartridge and necessarily heavier rifles and magazines merely increase their burden. In short, giving long-range rifles to line infantrymen without additional training is a waste of strategic resources, money, and time. This is not to say that specialized marksmen would not be able to take advantage of such a cartridge, but they would be better served by a specialized rifle firing a cartridge with higher velocity and better hit probability at range, not the inherently compromising GPC.

 
Unless the author has access to HUMINT or continuous satellite coverage of England, targeting Tony specifically, the above claims are completely unsupported by data, and appear to me to be a rather juvenile attempt at ad hominem. And a reader might ask what experience the author has in hitting targets with rifles.
 
Also, it was trivial to find a non sequitur;
 

Is a 25% worse trajectory, increased bolt stress, lower reliability, fewer rounds per magazine, and the introduction of an entirely new cartridge worth a 10% increase in energy per kilogram at half a kilometer?

 
I didn't see any data on reliability presented. Now 6.8SPC may very well be less reliable than 5.56, but in this context citation of empirical data is kind of a tradition.

Oh wait, here's another one;

Beyond (valid) concerns about the cartridge's extreme shoulder angle and lack of case taper, the case itself does not have enough internal volume to accept tracer or steel-cored armor piercing projectiles, except with the lightest bullets. Thus, it cannot fulfill the role of a GPC, as it is not a suitable military cartridge.


Poorly explained, but apparently leveraging off the myth that you can't have bullet bases or boattails intruding into the case past the base of the neck. My suspicion is that old wives tale dates back to cast bullets, and particularly the development of gas checks. There's a classic photo of bullet intrusion in one of Ken Waters' Pet Loads articles, I believe for the 6.5mm Remington Magnum, in which those looong 140 grain 6.5mm bullets protrude far, far into the case. I've not seen one of those sectioned round pics for the newer 5.56 rounds, but I would imagine that some of the .223/5.56 loads using 77 grain match HPs and similar bullets have notable intrusion.

In summary, I think most of us could write a 10-20 page critique of the article while leaving a half-dozen or so booboos for the reader to eviscerate.

 

 

Addressing in order:

1. I am not trying to impinge on Tony's honor or anything like that. I am just saying that, to my knowledge, he does not have a lot of first-hand experience shooting for accuracy at distance. I know he's shot many exotic rifles (and I'm very jealous, I assure you), but I don't get the impression that he's a marksman. I don't think this is an outlandish assumption to make, given his location. If Tony does have more firsthand experience than I assume, I urge him to say so, but in numerous conversations with him he never has.

I did not list my shooting experience because I did not want to make it a pissing match between Tony and I.

 

2. That is not a non-sequitur. It is unsourced, as you note, but I will only say in response that using a cartridge your feed ramps and magazines are not designed for is typically not good for reliability. It may have been unclear, but I was specifically talking about this in the context of a caliber retrofit. I don't see any reason purpose-designed 6.8mm rifles would be less reliable than anything else.

3. This has nothing to do with seating the bullet past the neck. Most military cartridges do that to some degree, certainly M855 does. The problem is that an 8g 6.5mm lead-free tracer would be very, very long. The tracer for 6.5x55 Swedish is 5.2 calibers long, and it's lead cored and is fairly light (7.78g, 120gr). With a projectile that long in the short Grendel case, you'd be eating up much of your powder capacity. If you had the real-estate, this might be OK, but with the 6.5 Grendel, you don't. Perhaps the wording I used was ambiguous, as tracers will physically fit in the case, but they eat up enough capacity that they grossly reduce muzzle velocity. Introducing a lead-free requirement into the mix aggravations things further. Lead-free tracers are a problem for any cartridge, but they especially impact the Grendel because of its short case. Lead-free is pretty much a requirement going forward, so I don't see this issue being resolved any time soon. 


Edited by BabyOlifant, 26 November 2013 - 0103 AM.


#12 BabyOlifant

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Posted 25 November 2013 - 2321 PM

I whipped up a model of 6.5 Grendel with an 8g lead-free tracer:

n70e0uU.png

 

The new bullet encroaches heavily on the case capacity of the cartridge. Performance would be significantly reduced, or pressure would have to be seriously increased (by about 10,000 PSI) to catch up to non-tracer loads. Further, at 6.2 calibers long, you would need a very tight rifling twist to stabilize this bullet (about 1-in-5").

 

This gets less egregious the lighter in projectile weight you go, but that sort of defeats the point, doesn't it?


Edited by BabyOlifant, 26 November 2013 - 0017 AM.


#13 Burncycle360

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Posted 26 November 2013 - 0255 AM

7.62 x 39 didn't perform so well at Stockton against children.

 

Seems to me that the 5.56 effectiveness varies from either MORE effective than 7.62 x 39 (if it fragments) or about as effective (if it doesn't) in that it will icepick a hole through the target, just like the 7.62 x 39.

 

Yes the 7.62mm is bigger, but the permanent crush cavity will be slightly (as in about 2mm) bigger.  It ain't gonna make up for poor shot placement.  Miss the heart or spine by 2mm? Then maybe 7.62 would have made a difference over 5.56, but come on.   And hitting harder? The perceived impact in either case is insignificant with adrenaline running through the target.  

 

Faster followup shots, flatter shooting, optics and lots of practice increase the chances of hits and only hits count. 

 

In scenarios where the baddies are engaging right at the edge of their effective envelope with 7.62 x 54r, of course you're not going to be able to overmatch them. You're using an intermediate cartridge and it is a compromise by nature.  Yeah there is room for improvement over 5.56 and 7.62 x 39 and I think we should improve upon them, but in situations like that a slightly tweaked and optimized bullet isn't going to make up for restrictive ROE that won't let you bring indirect fire to bear.  It's a procedural issue.


Edited by Burncycle360, 26 November 2013 - 0331 AM.


#14 BabyOlifant

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Posted 26 November 2013 - 0307 AM

Well said, Burncycle. I was thinking something very similar, myself. And don't forget, that 5.56 is significantly lighter than 7.62x39.



#15 Sebastian Balos

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Posted 26 November 2013 - 0519 AM

@Burncycle360

 

5.56 simply can't have the same stopping power as 7.62x39 if it doesn't fragment - lower energy, half the projectile weight and diameter, period. The difference of the cavity size is 2 mm? Do you have any source for this claim?

 

Why do you think 7.62 can't be put accurately where needed? Less accuracy of AK or training? BS if you ask me. The only advantage 5.56 may have is a lower recoil, so selective fire may be more accurate. Again, selective fire is of a distant secondary or tertiary importance compared to single shot stopping power and being more sensitive to hitting an obstacle (branches, leaves, heavy grass).

 

The reasoning behind 6.5-7 mm ammo is clear - go for 7.62x39-ish recoil (a little more may be tolerable for selective fire), with slightly smaller diameter round that would increase stopping power even without fragmentation (with fragmentation even more) and able to match 7.62x51 at longer ranges. IMHO, the suggested rounds might do pretty good job. Balance is the key, not just having a high mv or being "advanced" per se.



#16 BabyOlifant

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Posted 26 November 2013 - 0645 AM

@Burncycle360

 

5.56 simply can't have the same stopping power as 7.62x39 if it doesn't fragment - lower energy, half the projectile weight and diameter, period. The difference of the cavity size is 2 mm? Do you have any source for this claim?

 

Why do you think 7.62 can't be put accurately where needed? Less accuracy of AK or training? BS if you ask me. The only advantage 5.56 may have is a lower recoil, so selective fire may be more accurate. Again, selective fire is of a distant secondary or tertiary importance compared to single shot stopping power and being more sensitive to hitting an obstacle (branches, leaves, heavy grass).

 

The reasoning behind 6.5-7 mm ammo is clear - go for 7.62x39-ish recoil (a little more may be tolerable for selective fire), with slightly smaller diameter round that would increase stopping power even without fragmentation (with fragmentation even more) and able to match 7.62x51 at longer ranges. IMHO, the suggested rounds might do pretty good job. Balance is the key, not just having a high mv or being "advanced" per se.

 

You are asking him for a source when you've provided none for your own claims.

It seems to me, the human body is pretty squishy, and you're not shooting it with wadcutters that are going to make a neat little hole. Spitzers can't even make neat cut holes in paper, what makes you think they'll make neat, caliber-sized holes in tissue?

 

It's "common wisdom" that more bullet weight = better terminal effectiveness, but, y'know, I've never seen a study that suggests that. Do you have a study, something more than an anecdote, even, to back up this claim?


Edited by BabyOlifant, 26 November 2013 - 0646 AM.


#17 Ivanhoe

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Posted 26 November 2013 - 1256 PM

 

Why do you think 7.62 can't be put accurately where needed? Less accuracy of AK or training? BS if you ask me. The only advantage 5.56 may have is a lower recoil, so selective fire may be more accurate. Again, selective fire is of a distant secondary or tertiary importance compared to single shot stopping power and being more sensitive to hitting an obstacle (branches, leaves, heavy grass).

 

 

Folks frequently attribute characteristics to the cartridge design that are integral to the platform and to cartridge tolerances. There are civilian folks here in the US (and probably Canada too) that fart around with 7.62x39 in the AR platform*, and I have yet to read any thunderous condemnation from them concerning accuracy. Iffy mag feeding, yes. Yeah, the Mini-30 folks don't get minute-of-mosquito accuracy, but then the Mini-14 folks don't either; that's a Ruger thing, not a cartridge thing. If the US Army went to domestically manufactured 7.62x39 out of a Sig 556R or similar quality rifle, with a decent trigger and an appropriate optic, everybody would be bitching about ammo weight, not accuracy.

 

* Also 5.45 these days, since it is a common milsurp cartridge.



#18 Ivanhoe

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Posted 26 November 2013 - 1312 PM

1. I am not trying to impinge on Tony's honor or anything like that. I am just saying that, to my knowledge, he does not have a lot of first-hand experience shooting for accuracy at distance. I know he's shot many exotic rifles (and I'm very jealous, I assure you), but I don't get the impression that he's a marksman. I don't think this is an outlandish assumption to make, given his location. If Tony does have more firsthand experience than I assume, I urge him to say so, but in numerous conversations with him he never has.

In the articles I've read, Tony generally relies on the data and opinions of Brits and Americans who have been in the sandbox (and there are one or two gents who post in WOTT who have put metal on meat over there), rather than his own opinion. So if you're going to attack Tony's conclusions based on his personal shooting ability or lack thereof, it would be a lot more convincing if you attacked the conclusions of the guys in uniform whose conclusions Tony builds his case upon.

 

I did not list my shooting experience because I did not want to make it a pissing match between Tony and I.


Yet you keep going on and on about his shooting skills and experience, or lack thereof. Not really good form to piss on somebody's leg, then declare a no-pissing zone.



#19 BabyOlifant

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Posted 26 November 2013 - 1410 PM

 

1. I am not trying to impinge on Tony's honor or anything like that. I am just saying that, to my knowledge, he does not have a lot of first-hand experience shooting for accuracy at distance. I know he's shot many exotic rifles (and I'm very jealous, I assure you), but I don't get the impression that he's a marksman. I don't think this is an outlandish assumption to make, given his location. If Tony does have more firsthand experience than I assume, I urge him to say so, but in numerous conversations with him he never has.

In the articles I've read, Tony generally relies on the data and opinions of Brits and Americans who have been in the sandbox (and there are one or two gents who post in WOTT who have put metal on meat over there), rather than his own opinion. So if you're going to attack Tony's conclusions based on his personal shooting ability or lack thereof, it would be a lot more convincing if you attacked the conclusions of the guys in uniform whose conclusions Tony builds his case upon.

 

I did not list my shooting experience because I did not want to make it a pissing match between Tony and I.


Yet you keep going on and on about his shooting skills and experience, or lack thereof. Not really good form to piss on somebody's leg, then declare a no-pissing zone.

 

 

I will let Tony decide whether he feels offense at my conclusion. I think we're both civilized people, and if there's contention there, we can work it out.

 

Tony's GPC idea dates back to 1971, actually, so I have a hard time believing he formulated it out of whole cloth after taking the advice of servicemen. In fact, there are as many next-generation cartridge ideas (nearly) as there are veterans. Just because Tony has found some support among veterans does not automatically make his ideas... Bulletproof.  ;) 


Edited by BabyOlifant, 26 November 2013 - 1437 PM.


#20 Tony Williams

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Posted 26 November 2013 - 1622 PM

If I may intrude, I have a few comments….. B)

 

As I say in my GPC article (http://www.quarry.ni... Generation.htm ), 8g is I think too heavy for a feasible military 6.5mm lead-free bullet, especially once the need for even longer tracer bullets is taken into account, with 7g being around the practical maximum. That is why I stopped using the "6.5/8/800" designation some time ago, and why my GPC article shows two options for 6.5mm, with 8g (lead) and 7g (lead-free) bullets.

 

I have been careful not to specify too precisely the specification of a GPC because there is no one "right answer" – there is a "solution space" which runs from 6.35mm to 6.8mm calibre with variations in bullet weight and muzzle velocity accordingly. I use 6.5mm, with a muzzle energy of around 2,500 J, as a mid-point calibre merely for illustrative purposes.

 

Contrary to the The Case Against article (TCA), I do not particularly favour the 6.8mm SPC's case diameter: my GPC article includes notional rounds based on both the SPC and the Grendel case diameters (the Grendel's being the same as the 7.62x45 Czech mentioned in TCA). As far as size is concerned, both the Grendel and 6.8mm SPC are almost powerful enough, developing around 2,400 J. The 6.5mm Arisaka mentioned in TCA generated over 2,600 J from a 50mm-long case about the same diameter as the Grendel's over a century ago, without the benefit of modern powders, so the GPC should be usefully smaller as well as lighter (the Arisaka used a 9g spitzer bullet).

 

The bullet is the key to the GPC since it needs to have a significantly better ballistic coefficient than the 7.62mm M80; that enables it to catch up with and eventually surpass the M80 bullet in terms of velocity and ultimately energy as the range extends. Contrary to the TCA, I did not "specify that the bullet should be based on the 7N6 projectile of the Russian 5.45x39 cartridge"; I merely gave that as an example of a mass-produced military ball bullet which has a significantly better form factor than the M80, and assumed in my calculations of comparative ballistic performance that a GPC bullet would be able to match that form factor (in fact, I would hope that it could do better).

 

My key criticism of the TCA is the lack of context – in particular, that of the recent combat experience of US and UK forces in Afghanistan*. The weight advantages of 5.56mm weapons and ammunition become irrelevant when a substantial proportion of small-arms engagements take place beyond their effective range - they then become useless dead weight. No-one knows what future conflicts may involve, but it is predictable that the enemy will have long-range PKM LMGs available and will seek to use any range advantage whenever they can. The current practice of carrying rifles and MGs in both 5.56mm and 7.62mm at section/squad level reduces the fighting power of the section at long range and means that the two MG gunners cannot transfer ammunition should one of them run out or suffer a jam, and neither can the riflemen.

 

My own shooting experience has been questioned. In fact I started out as a target shooter, with my experience including competitions at Bisley at up to 1,000 yards. It was this which sparked my interest in ballistics and cartridge design, and led to my first GPC proposal. I haven't mentioned it before because it is not particularly relevant – it was a long time ago and what matters now is the recent experience of the infantry in combat. The concerns about the current calibres which I expressed in the GPC article come from them.

 

These concerns have clearly been recognised by the US Army. As I mention in the GPC article, a 2011 PEO Soldier report on Soldier Battlefield Effectiveness specified the need for general purpose rounds effective against a wide range of targets and emphasised that soldiers must be able to engage the threat facing them – whether that is at 8 or 800 metres. A 2010 ARDEC report into future army rifle ammunition tested various calibres from 5.56mm to 7.62mm and found that those between 6.35mm and 6.8mm offered the best characteristics. A 2012 report by AMU specified 6.5mm as being the optimum calibre for a future infantry rifle. Putting these together, it is clear that the US Army's research and marksmanship organisations would ideally like a general-purpose cartridge for portable small arms that would be of around 6.5mm calibre.

 

The US Army is currently conducting a 'Caliber Configuration Study' to support two new small-arms programmes, designated CLAWS (Combat Lightweight Automatic Weapon System) and LDAM (Lightweight Dismounted Automatic Machinegun). LDAM is seen as a support MMG (i.e. platoon or company level) with an effective range good enough to replace .50 BMG in such roles as well as the 7.62mm M240. The cartridge for this will clearly need to be bigger and more powerful than the 7.62mm. CLAWS is seen as the standard portable weapon family, which means that will need to offer a better long-range performance than 5.56mm can manage so that it can replace the 7.62mm MK48 as well as the 5.56mm M249 LMGs, plus assault rifles and DMRs, which indicates some form of GPC. It will be interesting to see what this study comes up with.

 

*Edit to add: my information concerning the recent combat experience of the US and UK armies does not just come from individual soldiers (although I get a lot of that too) but from official presentations by senior officers at military conferences I attend.


Edited by Tony Williams, 27 November 2013 - 0025 AM.





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