FUTURE INFANTRY SMALL ARMS
© Anthony G Williams
The original version of this article appeared in the Winter 2011 issue of the Small Arms Defense Journal and in the 1st Quarter 2012 issue of Small Arms Review
Last amended September 2012
Combat experience in Afghanistan is leading to some rapid changes in the small arms and ammunition carried by ISAF foot soldiers; and most especially by the US Army, USMC and the British Army and Royal Marines. The purpose of this article is to outline these changes, examine the lessons learned, and look ahead to examine the extent to which the growing variety of rifles, carbines, infantry automatic rifles (IARs) and light machine guns (LMGs) might be replaced in the near future by a smaller number of weapons without losing any capability.
Developments to Date
Before the Afghan conflict began, it was assumed that small-arms engagements would continue to take place within the traditional 300 metre limit, as they had in Iraq, and ISAF forces were equipped accordingly. The rifles and LMGs carried by the infantry on foot patrols were overwhelmingly in 5.56mm calibre, using the NATO standard SS109/M855 ammunition. The US forces used three principal weapons: the M16 rifle (favoured by the USMC), M4 Carbine (increasingly favoured by the US Army because its compactness makes it more suitable for urban fighting, the typical scenario in Iraq) and the M249 development of the FN Minimi LMG. Some 7.62mm weapons, most notably the M240 (FN MAG variant) and also some sniper and marksman rifles, were available for use in a support role when required. The British patrols used the L85A2 rifle, L86A2 Light Support Weapon (effectively an IAR) and the L110 LMG (FN Minimi Para). As with the US forces, the L7 GPMG (FN MAG) was available in support, and bolt-action 7.62mm sniper rifles were also in service.
These arrangements were thrown into disarray when faced with the very different circumstances of Afghanistan, where the Taliban noted the range limitation of the 5.56mm weapons and, wherever the terrain permitted, increasingly opted to engage ISAF troops from longer ranges. They could do this because as well as the ubiquitous but short-ranged AK family of assault rifles in 7.62x39 calibre, they have weapons chambered in the powerful Russian 7.62x54R round, equivalent in performance to the NATO 7.62x51. The principal weapons using this cartridge are the lightweight PKM belt-fed LMG and the Dragunov semi-automatic rifle. Both the British and US forces have reported that more than half of Taliban small-arms attacks are launched from ranges greater than 300 metres, out to as far as 900 metres. While the 5.56mm NATO weapons were previously claimed to be effective out to 450-600 metres, combat experience has shown that their performance falls off sharply beyond 300m - or even less, when used in short-barrelled weapons.
The adoption by US forces of replacements for the M855, in the form of the M855A1 (US Army) and MK318 Mod 0 (USMC), should resolve some of the problems with the NATO ammunition concerning erratic terminal effectiveness and poor barrier penetration. However, they will not help the UK and other NATO nations whose lawyers take the very literal interpretation of the Hague Convention prohibition of bullets "with a hard envelope which does not entirely cover the core" - which describes both of the US bullets. In any case, no 5.56mm developments will be able to eliminate the need for larger calibres to cover the longer ranges.
The immediate - and indeed, only immediately available - response of the US and UK forces was to redistribute existing 7.62mm weapons to the foot patrols, despite their unsuitability in terms of weight (FN MAG) or low rate of fire (bolt-action sniper rifles). The next stage has been to launch urgent requirements for new 7.62mm weapons. In machine guns, both the UK and USA are working on lightened versions of the FN MAG and also acquiring new lightweight MGs, comparable in weight and performance to the Taliban's PKM; the US already has the MK48, the 7.62mm version of the FN Minimi which the British also selected in mid-2011.
New rifles have also been acquired; the US had the advantage of already having selected the 7.62mm M110 SASS (Semi-Automatic Sniper System) and have also refurbished more than 5,000 of the old M14 rifles to the M14 EBR (Enhanced Battle Rifle) with modern furniture and accessories. These are proving very popular. The British have also acquired a 7.62mm semi-automatic sharpshooter rifle from the USA, the L129A1, which is also very popular. In contrast, the USMC has kept one eye on the needs of urban fighting and has rather controversially acquired a new, compact 5.56mm IAR to replace many of the M249s at section level; the HK416-based M27.
The Case for Change
So we now have the following rifles and MGs in service or in prospect, all intended to be carried by dismounted soldiers on patrol:
In the USA, the 5.56mm M4, M16, M27 and M249, plus the 7.62mm M14EBR, M110, MK48 and lightweight M240. That's a total of eight weapons, four in each calibre. In addition they have heavier support weapons and bolt-action sniper rifles, plus special forces use the MK12 5.56mm and the MK17 (FN SCAR-H) 7.62mm rifle, but none of these are included in this count.
The UK forces have the 5.56mm L85A2, L86A2, L110, plus the 7.62mm L129A1, L7 GPMG, and 7.62mm FN Minimi: a total of six weapons, with three in each calibre. Again, there are bolt-action sniper rifles in use as well as these, and special forces use other rifles in 5.56mm and 7.62mm calibres.
Such a variety of weapons carries some self-evident drawbacks in complicating and increasing the cost of acquisition, logistics, maintenance and training. Less obviously, there may also be penalties in combat. Those troops armed with 7.62mm weapons will be penalised by the weight of the guns and ammunition (7.62mm cartridges weigh twice as much as 5.56mm), plus the much heavier recoil in rifles which slows down aimed semi-auto fire and makes automatic fire impractical. The bigger and less wieldy weapons are also less suited to urban fighting. On the other hand, those with 5.56mm weapons will be able to make little or no contribution to long-range engagements - not even in supplying their ammunition to other members of their section. When combat ranges may fluctuate rapidly it is necessary to carry weapons in both calibres to cover the tactical demands but this reduces the potential firepower of a section in both short-range and long-range engagements.
The urgent need to plug gaps in weapon capability has made the current proliferation of firearms inevitable for the time being, but this situation raises an obvious issue: when planning the next generation of weapons, is it possible to provide a similar range of capabilities with a smaller number of guns, each effective at all normal small-arms ranges?
The key question is: what capabilities do we need from infantry rifles and portable MGs? The answer to this will determine the characteristics of the ammunition, the guns and the weapon sights. These characteristics will also be influenced by new developments in all three fields.
The US Army's Program Executive Office Soldier, published in August 2011 a study titled: Soldier Battlefield Effectiveness. This analysis covers a lot of ground and is well worth reading, but I will concentrate here on those parts concerning weapon performance, which include a number of important points which are relevant to the design of future infantry rifles. Here are some quotes:
"A Soldier must be able to engage the threat he’s faced with – whether it’s at eight meters or 800."
"Ultimately, Army service rifles must be general purpose in nature and embody a series of tradeoffs that balance optimum performance for a wide range of possible missions in a range of operating environments. With global missions taking Soldiers from islands to mountains and jungles to deserts, the Army can’t buy 1.1 million new service rifles every time it’s called upon to operate in a different environment. Further, the service rifle needs to work well in the hands of Soldiers from the 5th percentile females to 95th percentile males in terms of body size and composition. Inherent in a system’s ergonomics are the significant design tradeoffs of caliber and barrel length."
"Rather than trading off characteristics, some may suggest simply increasing the variety of platforms in a squad. While it’s beneficial to have a mix of capabilities, too much system diversity reduces a unit’s ability to cross level magazines and ammunition in a fire fight. On a much larger scale, standardization between units and among allies facilitates logistical support."
"During the course of a Soldier’s patrol, he may face a variety of threat situations. He could be working a checkpoint that is approached by enemy combatants in a vehicle. He could be engaging in a fire fight with insurgents clad only in soft garments. Or he could be facing an enemy taking cover behind walls or doors. To be effective in all scenarios, a Soldier needs to have true “general purpose” rounds in his weapon magazine that are accurate and effective against a wide range of targets."
"Looking even further out, the Defense Advanced Research Projects Agency is leading an initiative for improved optics through its Dynamic Image Gunsight Optic (DInGO) program. The goal of the DInGO program is to develop a rifle scope that will turn every soldier into a marksman over the full lethal range of combat rifle, allowing accurate engagement of targets by automatically making all of the ballistic adjustments needed to hit the target."
"Weapons….must be accurate and capable of engaging the enemy at overmatch distances."
These clearly indicate the value of a general-purpose rifle firing general-purpose ammunition, suitable for engaging the enemy at all small-arms combat distances.
This leads to the following capabilities which should be sought in new small arms, beyond the obvious ones of reliability, robustness, reliability, good ergonomics, reliability, easy maintenance, reliability, ability to accept a wide range of accessories, and of course reliability in extended combat conditions:
1. The rifle should be effective out to the maximum feasible range for small-arms engagements; at least 800 metres. The definition of effectiveness to include hit probability, barrier penetration and rapid incapacitation of personnel. It should also be accurate enough to hit point targets out to at least 600 metres.
2. The rifle should be as compact as possible, so that it is handy for urban warfare and for carrying in cramped vehicles and helos.
3. The recoil should be light enough to facilitate training, rapid and accurate semi-automatic fire, and controllable burst fire.
4. The rifle should be capable of maintaining a high rate of fire for several minutes without harmful effects.
5. The LMG should use the same ammunition as the rifle, be belt-fed and be capable of accurate and sustained automatic fire out to at least 1,000 metres.
6. The guns and their ammunition should be as light as they can be without compromising any of the above requirements.
I will now consider the three elements - ammunition, guns and sights - to examine the implications of these requirements.
In this section I will be considering ammunition performance; essentially, ballistics. I don't intend to consider advanced cartridge technologies such as the caseless-telescoped and plastic-cased-telescoped rounds being developed as a part of the US Lightweight Small Arms Technologies programme. If one of these is eventually selected for production, it will bring the considerable benefits of a substantial weight reduction, but it won't alter such matters as the choice of calibre, bullet weight and type, external and terminal ballistics.
I have previously discussed these issues at some length, especially in THIS presentation, so I will only summarise them here. It is both possible and desirable to develop one general-purpose round (GPC for short) which could replace both the 5.56mm and the 7.62mm in portable infantry guns; this would halve the number of different weapons and would also ensure that each weapon has a much wider range of capabilities. It would significantly reduce the weight and recoil compared with 7.62mm ammunition, while improving the range, barrier penetration and terminal effectiveness compared with 5.56mm.
If the GPC is to be effective at long range, it must match the standard 7.62mm NATO ball round in its hit probability (i.e. trajectory, flight time and wind-drift) and its effectiveness (i.e. retained energy and barrier penetration) out to at least 1,000 metres. However, if it is to reduce the ammunition weight and recoil compared with 7.62mm, it must be smaller and less powerful. This conflict can be resolved by selecting a calibre intermediate between the 5.56mm and 7.62mm, with a low-drag bullet which will lose velocity (and therefore energy) more slowly than the 7.62mm ball. Muzzle energy will be lower than the 7.62mm (but appreciably higher than the 5.56mm) but the right specification of low-drag bullet will eventually catch up with and even surpass the 7.62mm in retained energy.
In practical terms, the smallest calibre likely to deliver a performance comparable with the 7.62mm is 6.35mm, while the largest which would enable recoil and weight to be kept in check is 7mm. Exactly which calibre proves to be the best compromise will be determined by more detailed analysis, comprehensive testing and preferably combat experience. Initial calculations indicate that a muzzle energy in the region of 2,500 joules (1,850 ft/lbs), compared with 1,700 J for the 5.56mm and 3,200+ J for the 7.62mm, will be required. Experience of existing cartridges in this class indicates that the weight and free recoil energy of the GPC will be mid-way between the 5.56mm and 7.62mm, but the perceived recoil will be much closer to 5.56mm, thereby maintaining good controllability.
The US Army's ARDEC Small Caliber Munitions Technology Branch conducted an analysis of calibres for future infantry weapons, with the results emerging in March 2011. A wide range of criteria were examined including: penetration; terminal effectiveness; accuracy; initial, retained and striking energy; wind drift; stowed kills; and recoil. 5.56mm and 7.62mm rounds were tested at various ranges in comparison with 6mm, 6.35mm and 6.8mm, in all cases when loaded with similar lead-free copper+steel bullets (representative of the M855A1 EPR type). The conclusion of the study confirmed that calibres in the 6.35mm to 6.8mm range deliver the optimum characteristics for use in a standard military rifle. Informal sources indicate that this study has been followed by an examination of the optimum infantry rifle cartridge by the US Army's Marksmanship Unit (AMU), which settled on a 6.5mm calibre firing low-drag bullets for a good long-range performance. These conclusions are given emphasis by a growing view that the next US rifle should be effective at ranges of up to 600m and that 5.56mm could not deliver this, no matter what bullets were loaded.
There is a fashion for ever-shorter barrels, which comes at a price. There is a direct link between barrel length and ammunition design: to achieve any specified ballistics with a short barrel rather than a long one needs a more powerful cartridge to accelerate the bullet more rapidly; this will be bigger and heavier, and generate more pressure, barrel heat and wear, plus more recoil, muzzle flash and blast. The larger quantity of higher pressure gas leaving the muzzle will require a bigger and heavier suppressor. These are all significant disadvantages, which must be weighed against the greater handiness of short-barrelled carbines in vehicles and in urban fighting. A folding stock can resolve the carrying problem but doesn't help in urban fighting when the stock must be extended to provide controllability.
Another option is to have barrels of different lengths which can be changed depending on the circumstances, but that may not be convenient, particularly if the ranges keep changing during a patrol (for example, a section might be searching a village but then be attacked at long range as they leave). A further option is to select a compromise barrel length, but this will result in a gun which is longer than is desirable in urban fighting. It will also have a reduced long-range performance unless the power of the cartridge is increased to deliver the same performance from a shorter barrel, in which case the ammunition weight, recoil, and muzzle flash and blast will be increased. The obvious solution to this dilemma is to adopt a bullpup configuration, with the action and magazine located at the back of the gun, behind the pistol grip.
The proposal of a bullpup is controversial since the US Army has never used them and appears to dislike them, so requires some further justification. I explain the pros and cons of bullpup versus traditional layouts in detail in THIS article, so will only summarise the conclusions here:
All weapon designs have their own pros and cons which need to be weighed up against each other to determine the best overall compromise. The major advantage of a bullpup is a saving of around 20-25cm (8-10 inches) in overall length for the same length barrel is very significant in modern combat. The other major bullpup advantage is the much superior weight balance when UGLs and other increasingly common accessories are added to the gun. Furthermore, with an optimised design of the type suggested in the article linked to above, there need no longer be any serious practical objections to the bullpup layout: those raised by supporters of traditional rifles can either be addressed, or on examination are not significant and usually boil down to personal preference. The latest versions of some bullpups, such as the Israeli X95, EF-88 Austeyr and even the Chinese QBZ95-1, are gradually addressing the ergonomic and other problems which are typical of the first generation of bullpups.
In addition, the adoption of a GPC as proposed here would strengthen the case for the bullpup. At the moment, it is possible to argue that 5.56mm rifles can have short barrels because they are increasingly seen as short-range weapons. On the other hand, 7.62mm rifles are being introduced for the long-range role and therefore don't need to be very compact for urban warfare. However, a single general-purpose infantry rifle in a general-purpose calibre must be well suited to both urban fighting and the long-range role. The bullpup layout achieves this and is effectively two existing weapons - a rifle and a carbine - in one.
One issue which often receives little attention is recoil control, which as already observed is important in a rifle in order to facilitate training, rapid and accurate semi-automatic fire and controllable automatic fire. In guns of similar type, recoil is largely a function of the gun weight and the cartridge power (specifically, the momentum - mass × velocity - as opposed to energy - mass × velocity squared). However, the gun action can also have a significant effect, with advantages being demonstrated by soft-recoil mechanisms or even opposed-piston types like the AK-107. The US Army has recently been researching this and achieved reductions in the peak recoil force of up to 90% by using a counter-mass principle; but this would inevitably add weight. Controllability in automatic fire can also be enhanced simply by reducing the rate of fire. The very high cyclic rate common in modern 5.56mm small arms has little if any practical benefit and leads to more rapid ammunition exhaustion and barrel heating as well as greater cumulative recoil.
To achieve a high volume of automatic fire, as may be involved in fighting off a close-range attack, usually requires a heavier barrel. However, the US HPAWA project (High Performance Alloys for Weapon Applications) aims to result in barrels which will withstand far heavier rates of sustained fire, so that MGs can be issued with only one barrel. Good progress has since been reported by ARDEC (HERE) in the development of highly temperature-resistant cobalt alloys. If such alloys reach production, this should enable a standard rifle to offer volumes of fire comparable with an IAR without any increase in barrel weight. The problem of cook-off after an intense engagement could be addressed, if need be, by arranging for the gun to fire from an open bolt in automatic mode (although the USMC has not required this of their new IAR). In other words, we could replace three weapons (carbine, rifle and IAR) with one.
The design of the belt-fed LMG to accompany this rifle has not been discussed here, since the same design problems do not apply and existing designs could be adapted well enough to a new cartridge. The adoption of a general-purpose intermediate cartridge developing significantly less recoil than the 7.62mm would however obviously allow the weight of the gun to be reduced without compromising reliability, which with the significantly lighter ammunition would deliver a substantial reduction in the weight currently carried by GPMG gunners and ammunition carriers.
The use of telescopic rifle sights has brought a great improvement in accurate long-range fire. If nothing else, they give a much better chance of seeing the target. Rifle and MG sights are currently making further advances in capability. Variable magnification has been available on the specialist market for a very long time, and has now been joined by dual-magnification military sights, initially from Elcan (with 1-4x and 1.5-6x versions available), equipping the infantry with a sight suitable for both short and long-range use.
The addition of electronics is bringing even more dramatic advances. As a minimum, this will include a laser rangefinder linked to a ballistic computer to indicate the point of aim, correcting for up and downhill angles and indicating weapon cant. Such sights are already available on the civilian market. Future sights may also include some or all of the following, depending on size and cost limitations: optronic sights with image enhancement and digital zoom; night-time capability with a combination of image intensifying and thermal imaging elements; and crosswind measurement & correction. Optronic sights will permit the recording of the image in the sights each time the soldier takes aim and fires, which will be a great aid to training as well as after-battle analysis.
Even more remarkable is the LIDAR (Laser Identification Detection And Ranging) unit developed by the Israeli Soreq Nuclear Research Center. This works by firing a laser beam at the target, the reflection being captured by an array of photodiodes. Fluctuations in the signals received by the photodiodes are used to detect the direction and velocity of any cross wind. Something like this may well have an application in the U.S. Defense Advanced Research Projects Agency (DARPA) One Shot Advanced Sighting System, a next-generation sniper scope program, for which Lockheed Martin received a DARPA award in 2008 to develop crosswind measurement capabilities to increase target accuracy of a soldier's initial shot. The One Shot program is intended to enable snipers to be on target with the first round, under crosswind conditions, up to the maximum effective range of the weapon: a target of 65% probability of a first-round hit at up to 1,500 metres has been set (presumably when using large-calibre long-range sniper rifles). A follow-up project is the DARPA Dynamic Image Gunsight Optic system (DInGO) for which LockMart was awarded a development contract in 2010. In the same year, the US military stated a requirement for a 1-4× day/night sight, merging thermal and light intensifying images, with a built-in rangefinder (and possibly a laser pointer), with a 3 lb (1.36 kg) weight, low power consumption and a price of $3-5,000.
What all of this means is that in the foreseeable future we will see affordable day/night variable magnification sights which will detect cross-winds and incorporate a laser rangefinder and a ballistic computer linked to the sighting reticule. With this kind of technology, such issues as weapon cant and the effects of firing up or down hill can also be taken into account. All the soldier will have to do is to lase the target and the sights will automatically indicate the correct aiming mark to put the bullets into the target area.
Initially, such sights will be bulky, heavy and expensive, and thereby restricted to snipers, but it is safe to predict that within the foreseeable future they will become compact, light and cheap enough for general issue. This is enormously important because it means that the main objection to providing rifles with a long-range capability - that most soldiers will never be well-enough trained to hit anything at such ranges - is removed. In conjunction with a long-barrelled standard rifle and long-range intermediate ammunition (and assuming a fundamentally accurate weapon and good-quality ammunition production), this also means that a separate DMR or sharpshooter rifle may no longer be required. Potentially we could therefore replace four existing guns (carbine, rifle, IAR, DMR) with one.
Clearly, these new sights should greatly extend the effective range of rifle fire, but only if the ammunition and guns are capable of delivering this. The same sights and ammunition will of course also transform the long-range effectiveness of the belt-fed LMG, although the sustained-fire capability of a rifle with an advanced-alloy barrel may mean that fewer MGs will be needed.
So we have reduced our two cartridges to one GPC, and our six or eight different guns to two - the general-purpose infantry rifle and the belt-fed LMG - without any loss in capability. The practical and financial advantages of such a simplification would be huge, as would the boost to the capability of the rifleman in whatever tactical circumstances may arise.
Various attempts have of course been made to introduce an intermediate round before, one of the first being the .276 Pedersen of the late 1920s. After exhaustive tests this was recommended for adoption by the US Army and the British were also very interested, but it was cancelled principally for financial reasons. The modern equivalent is the 7x46 UIAC (Universal Infantry Assault Cartridge), an experimental round being developed by Cris Murray who was involved in the development of the 6.8mm Remington SPC. The UIAC represents the top end of the calibre and power range suitable for a GPC: at the bottom end of the scale is the 6.5mm Grendel.
All of the technologies which I have mentioned are either available now or are very likely to be available by the time the next generation of small arms has been developed.
If LSAT succeeds (and the plastic-cased telescoped element is currently looking promising), then a dramatic weight reduction can be added to the other advantages; it would mean that a GPC could weigh about the same as the current 5.56mm.
Now all we need is the people in the right places with the vision to see and drive towards what is possible, rather than simply going down the same old road because that's what we've always done. It's time for small arms to leave the 20th century.
Cartridges (from left to right): 5.56x45 NATO, 6.5x38 Grendel, 7x46 UIAC, .276 Pedersen, 7.62x51 NATO, 7.62x54R Russian (PKM), 7.62x39 Russian (AK).
The 6.5mm Grendel and 7x46 UIAC are not current military cartridges, but represent the top and bottom of the calibre and power range likely to prove suitable for a general-purpose military small-arms cartridge.
|Testing time, courtesy
DCMS Shrivenham (except bottom right, courtesy of Heckler & Koch).
Below left, the 7.62mm SCAR H is light for such a powerful cartridge; the gun jumped considerably and the target had to be reacquired for each shot.
Below right: the 7.62mm HK417 is heavier, steadier and more comfortable to shoot
Middle left: the 7.62mm HK G3K carbine is decidedly unpleasant, partly because of the small, hard butt-plate with this telescoping stock; affectionately and accurately dubbed the "meat tenderiser". This forcibly drove home the fact that butt design makes a big difference to shooting comfort (the bruise eventually faded)
Middle right: the enemy - a Dragunov. Also unpleasant to shoot, I had to reacquire the view through the scope after each shot
Bottom left: a bullpup rifle in an intermediate calibre was once adopted for the British Army.This is the 'Rifle, No.9 Mk 1' chambered in the '7 mm Mk 1Z' (7x43) cartridge, better known as the EM-2 in .280/30. It was cancelled for political reasons in 1951, before any could reach the troops.
Bottom right: recoil test with three Heckler & Koch rifles: the HK416 in 5.56x45, HK416 in 6.8x43, and HK417 in 7.62x51. Although the calculated recoil of the 6.8x43 (Remington), a typical intermediate cartridge, is midway between the two other rifles, the perceived recoil is much closer to the 5.56mm. Timed tests in the USA have revealed that accurate rapid fire is just as easy with 6.8mm as 5.56mm rifles.
A history of the development of assault rifles and their ammunition is HERE