FUTURE INFANTRY SMALL ARMS

© Anthony G Williams

Original version July 2010, amended April and November 2011

This article appeared in the  Winter 2011 issue of the Small Arms Defense Journal

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 some 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.

I suggest that the following capabilities 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.

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.

Ammunition

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 round 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 ammunition is to be effective at long range, it must match the standard 7.62mm NATO ball round in its trajectory, retained energy and barrier penetration out to 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. Other things being equal, low-drag bullets are heavier than usual, so to keep recoil in check need to be fired at a lower velocity. 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 practical terms, the smallest calibre likely to deliver a performance comparable with the 7.62mm is 6.5mm, 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 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 recently 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. The existing 5.56mm and 7.62mm rounds were tested at various ranges in comparison with 6.5mm and 7mm, in all cases when loaded with similar lead-free bullets (copper or copper+steel - the latter representative of the M855A1). The conclusion of the study confirmed that calibres in the 6.5mm to 7.0mm range deliver the optimum characteristics for use in military small arms. This conclusion is supported 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. This issue has since been followed up by a Joint Caliber Working Group sponsored by the TSWG Tactical Operations Support Subgroup.

Gun Design

The need for good long-range performance combined with a short overall length for handiness in urban fighting and in vehicles causes problems for traditional rifles, since the first requires a long barrel and the second a short one. A folding stock can resolve the carrying problem but doesn't help in urban fighting when the stock must be extended to provide controllability.

One 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). Another option is to select a compromise barrel length, but this will result in a gun which is longer than is desirable in urban fighting and which will 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, while the British Army has been put off them by the long and painful saga of the SA80, 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 them here.

There are three principal objections to a bullpup:

1. Poor ergonomics: the location of the action and magazine well to the rear of the pistol grip makes operating the controls and changing magazines more difficult. This is particularly an issue with the SA80.

2. Lack of ambidexterity: most bullpups (although not the SA80) can be converted to left-hand use, but that takes some time to achieve so can't be done in the heat of battle. This means that users can't switch shoulders to aim round the corner of a building, for instance, without being hit in the face by their own ejected cases.

3. Lack of ability to adjust the stock length to allow for the wearing of body armour: again, a particular problem with the SA80 which has quite a long stock.

Apart from these practical concerns, some users dislike the rearward weight balance of the bullpup and the proximity of the action to the firer's head in case of a chamber explosion.
There are responses to all of these objections:

1. The ergonomics do not have to be as poor as the SA80's: the latest version of the Israeli Tavor, for instance, has controls which match those of the M16 and M4 in location and operation, since it was designed to replace them.

2. There are various ways of achieving ambidexterity. The FN F2000 uses a forward ejection tube, which carries the spent cases to the front of the gun before they are expelled. The new Beretta ARX-160, although not a bullpup, has a mechanism which changes the case ejection side at the flick of a switch. The STK SAR-21 from Singapore has a simpler solution for emergency left-hand use: a large and effective case deflector.

3. An adjustable stock could be provided if the gun action behind the magazine were designed to be shorter: something which hasn't happened so far since there has been no call for it. However, that should not be difficult to achieve in a new design.

Gun balance is, to a great extent, a matter of what you are used to. Some bullpup users prefer the rearwards weight balance, arguing that it is easier to hold one-handed or for extended periods, and makes the rifle quicker to change aim. What is undoubtedly true is that a bullpup is far more evenly balanced once an under-barrel grenade launcher, large electro-optical sights and other tactical kit (e.g. torches) start being added: a traditional rifle then becomes massively front-heavy.

The firer's head can be shielded from the action by using a tough kevlar cheek-piece, as with the STK SAR-21; this could be designed to flip quickly from one side to the other in conjunction with a switchable-side ejection system like the ARX-160's.

It is worth emphasising the key argument in favour of the bullpup: the design reduces the overall gun length by some eight inches for the same barrel length, which is a huge reduction. This is not just an advantage in urban fighting; it also facilitates fitting a suppressor, which is increasingly popular to reduce muzzle blast and flash and make firers more difficult to locate (it also protects the firer from long-term hearing damage). With barrels of the same length, a bullpup with a suppressor will be about the same total length as a traditional rifle without one.
 

IIn addition, the adoption of a general-purpose intermediate round 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. As previously mentioned, this combination can be achieved with a modular traditional design with quick-change barrels of different lengths (as most recent designs offer), especially if the action design also allows the stock to be fully telescoped. However, the bullpup layout does not require any such changes, and it 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.

Sights

Rifle and MG sights are currently making great 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, most obviously in night-vision capability. In 2010 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. With this kind of technology, such issues as air pressure, weapon cant and the effects of firing up or down hill can also be taken into account in providing an aiming solution.

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. This may well have an application in the DARPA One Shot next-generation sniper scope program. 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).

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 bulets 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.

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.

Conclusion

So we have reduced our two cartridges to one, 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.

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 an intermediate round would 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 20^th century.

Postscript

After this article was written, I became aware of the online document from the US Army's Program Executive Office Soldier: 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 can be used to support the argument for a general-purpose rifle firing general-purpose ammunition. 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."

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 judged to be 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