Is the USA about to force the rest of NATO to change calibres again?

Improved Individual Carbine from Colt

Two new US new small arms research programs suggest that this may be the case.

Since the beginning of the new millennium, US future small arms development has been focused on two separate programs: the Improved Individual Carbine Competition (IICC) and the Lightweight Small Arms Technology (LSAT) programs. At the beginning of this year, it became apparent that both initiatives were unlikely to lead to a new system being adopted. In fact, they have now been superseded by two new programs that will commence in early 2014 – the Combat Lightweight Automatic Weapon System (CLAWS) and the Lightweight Dismounted Automatic Machine-gun (LDAM).

These are likely to impact the UK and other NATO armies, so it may be worth assessing what they propose to achieve.

Before doing so, a review existing initiatives seeks to provide an understanding of the context and thinking behind the USA’s small arms strategy and the drivers of future technology in this area.

The Improved Individual Carbine Competition (IICC)

The US Army’s M16 / M4 assault rifle family has been in service for 50 years, longer than any other service rifle. In 2010, the US Army announced a new small arms initiative called the Improved Individual Carbine (IC) Competition

The aim of this program was to select a new weapon to replace the US Army’s existing M4 carbine. The key requirements were improved accuracy, reliability and durability; the capability to fire semi-automatic single shots and fully automatic bursts (instead of 3-round bursts); an integrated rail system to accept MIL-STD-1913 accessories; and fully ambidextrous controls. Costs were also a factor.

While the competition was open to any calibre, any manufacturer who submitted a candidate weapon that was not chambered for 5.56×45mm NATO and / or 7.62×51mm NATO was required to provide 500,000 rounds of test ammunition.

The extra financial burden this would have imposed essentially discouraged entrants from proposing a new calibre, even though two promising options already existed: the 6.8x43mm Remington SPC and the 6.5x39mm Grendel.

In terms of process, an initial familiarisation period was to be followed by a three-phase test and evaluation.

Phase I evaluated the ability of each weapon to mount optics, suppressors and other accessories.

Phase II involved firing the weapons to determine accuracy, reliability and durability with the contenders being whittled down to a shortlist of three. As it was, five weapons were selected for on-going evaluation: Colt’s Enhanced M4, the Heckler & Koch HK416A5, the FN SCAR, the Remington ACR, the ADCOR Defense BEAR Elite, and, a late entrant, the Beretta ARX-160.

Improved Individual Carbine from Colt
Improved Individual Carbine from Colt

Phase III, if it had gone ahead, would have included with soldier evaluation and contract negotiations.

The winner of the competition had to deliver a “measurable improvement” over the legacy M4 carbine to replace it. One of the many requirements was defined as the ability to fire 3,592 rounds between failures.

In 1990, the requirement for the original M4 had been only 600 rounds, while the current M4A1 achieves 1,600 rounds.

The Army stated that if no IC contender met the requirement it would resort to using an enhanced version of the current M4.

In other words, there was no guarantee that the winner of the IC competition would be adopted.

Since Colt was already developing an improved M4A1 carbine in parallel with the IC competition (and incorporating what it had learned from competitors’ designs along the way) and which, in any event, would be purchased through 2018, the IC competition began to look like a somewhat pointless exercise.

In May 2013, the US Army announced it was considering cancelling the Individual Carbine competition before Phase III commenced.

This angered the Senate’s Armed Forces Committee, who even considered passing a bill to force the Army to complete the competition. But in June 2013, the US Army announced that it was not cancelling but “concluding” the IC competition on the grounds none of the submitted weapons met the minimum performance requirements needed to continue to the next stage of the evaluation.

This avoided congressional interference. Moreover, it also dodged the real issue behind the cancellation: the failure of the US Army’s new 5.56 mm M855A1 Enhanced Performance Round (EPR) ammunition.

After complaints about the US Army’s existing 5.56 mm M855 NATO standard ammunition, a refined version was developed.

To deliver increased velocity, energy and improved terminal effectiveness, it had a much higher chamber pressure (62,000 psi versus 55,000 psi).

However, this caused increased barrel wear and premature failure of the bolt and other components. What was astonishing about the M855A1 EPR program was that it introduced a new ammunition into service without properly evaluating how it would work with the M4.

Everyone simply assumed that the new ammunition work in existing weapons, simply because it was physically similar to the round it replaced. As the IC competition proceeded, an alarming number of weapon failures began to derail it. The US Army realised that it couldn’t select a new carbine until it had perfected the ammunition it would fire.

It isn’t clear what will happen with the M855A1 round now, but unless the US Army is happy for it to negatively impact the durability of its entire M4 inventory, it will either have to develop a new round, return to using the previous M855 ammunition type or switch to something completely different.

In September 2013, the Pentagon Inspector General’s Department published an audit of the Individual Carbine competition.

It concluded that the US Army had wasted $14 million failing to select a new rifle it did not need. Cancelling the program prior to Phase III saved $40 million. But it would have cost $2.52 billion to buy the 501,289 carbines the Army planned to procure over a 20-year cycle.

The Army’s own analysis suggested the procurement could have been delayed for a decade with no impact on combat readiness.

Lightweight Small Arms Technology

The Lightweight Small Arms Technologies (LSAT) program was funded by the US Joint Service Small Arms Program (JSSAP), with the goal of significantly reducing the weight of small arms and ammunition. Feedback from operations in Iraq and Afghanistan, as well as the accumulated insight from previous research programs, suggested that lightening the infantryman’s combat load burden was essential to increasing combat effectiveness and survivability on the modern battlefield.

LSAT ammunition varieties. On the left standard 5.56 mm NATO. Centre: Caseless 5.56 mm ammunition. Right: Cased-telescoped 5.56 mm ammunition
LSAT ammunition varieties. On the left standard 5.56 mm NATO. Centre: Caseless 5.56 mm ammunition. Right: Cased-telescoped 5.56 mm ammunition

Following a series of unsuccessful previous programs to investigate potential technologies (including SPIW, the Future Rifle Program, ACR, and OICW), it was hoped that the LSAT program would finally provide a viable future technology to replace legacy small arms.

LSAT was initiated in 2004 with the development team comprising of a consortium of companies led by AAI Corporation.

Two weight saving ammunition types were proposed: plastic cased-telescoped ammunition (CTA), and caseless ammunition (CLA) based on Dynamit Nobel’s HITP propellant which was moulded to form a cartridge around the projectile.

This solution had previously been chosen for Germany’s ambitious 4.7 mm G11project.

The technology was never perfected and development was ultimately abandoned, bankrupting Heckler & Koch in the process.

In addition to the two lightweight ammunition varieties, the other area of focus for LSAT was to produce a light machine gun capable of replacing the M249 5.56 mm SAW. The LSAT LMG prototype was to serve as a test-bed and technology demonstrator.

To minimise risk, the program prioritised the development of the polymer cased-telescoped ammunition variant ahead of the caseless ammunition variety.

Prototype LSAT 5.56 mm LMG - it weighs 11.1 lb. compared to 17.6 lb. for a standard M249 SAW.
Prototype LSAT 5.56 mm LMG – it weighs 11.1 lb. compared to 17.6 lb. for a standard M249 SAW.

By 2008, the program had produced working prototypes for both ammunition types and for the LMG weapon designed to fire them.

Despite encouraging early tests, the US Army was reluctant to commit additional funding to the LSAT program. This hesitation may have something to do with various routine development issues. In particular, LSAT weapons have a more complex operating mechanism than legacy weapons. Problems included feed system functioning and reliability, component durability, premature barrel wear and throat erosion.

There were also concerns that making the weapon soldier proof would increase weapon weight resulting in only a marginal weight saving versus the M249.

LSAT 5.56 mm Carbine based on same technology as LSAT LMG, but with little or no weight saving versus legacy M4A1 Carbine.
LSAT 5.56 mm Carbine based on same technology as LSAT LMG, but with little or no weight saving versus legacy M4A1 Carbine.

So, the only real advantage lay in the reduction of ammunition weight, with CTA ammunition contributing to a 30% reduction and CLA ammunition, to a 40% reduction.

Meanwhile, polymer cased versions of existing brass cartridge technology were now beginning to deliver similar weight benefits in legacy weapons.

While there was no doubt that LSAT had significant potential, it would require a completely new infrastructure to manufacture the ammunition and a huge effort to train soldiers to use a completely new weapon type.

Budget estimates suggested that the costs of changing would be massive.

So, despite the program’s attraction, the risks seemed to outweigh the benefits.

Typically, when US military research programs reach a certain level of maturity, they must be demonstrated to the program sponsor to evaluate progress. The program sponsor must then issue a requirement for further research to proceed (and be funded).

Technology Readiness Levels
Technology Readiness Levels

US Technology Readiness Levels (TRLS) are used by the US DoD to measure used to assess the maturity of new technologies during its development and in some cases during early operations. At TRL 7, a prototype system reached near or actual readiness to be deployed as an operational system.

When LSAT reached required level of development, TRL7 status, it was duly shown to the US Army top brass, but no requirement was forthcoming.


The LSAT LMG is supposed to save 20-30% weapon weight versus M249 SAW. In reality, making LSAT durable and soldier-proof could make the final weight saving marginal.

Despite this, AAI managed to secure on-going funding for LSAT in August 2013.

This was in clear contradiction to the US DoD’s policy on technical research.

However, AAI has received less than $3 million of additional funding – a drop in the ocean compared to the IC competition budget.

So, it is reasonable to assume that this is another US small arms program that will be consigned to history.

Where to next?

With the failure of the IC competition and uncertainty hanging over LSAT, the US Army has no future small arms in its development pipeline.

This is surprising, because feedback from recent combat deployments suggests that the need to reduce weight burdens remains paramount.

More important, there is a clear requirement to be able to engage targets beyond the 300 metres range limit of 5.56 mm NATO ammunition.

As noted previously, 5.56 mm remains a controversial ammunition type. Five separate issues with this calibre have been identified:

  • Lack of effective range (it was always assumed that 5.56 mm NATO would be effective to 500 metres; indeed on ranges, experienced shooters have shown that they can hit targets at 800 metres – in reality, accurate shot placement in combat at long ranges is difficult to achieve)
  • Susceptibility to wind drift (a lack of range has a lot to do with the ease with which a light breeze can deflect the light 5.56 mm bullet off target)
  • Poor barrier penetration (the energy of a 5.56 mm round can easily be absorbed or depleted by any barrier it has to pass thorough en route to a target, including light cover, trees, car doors, thick clothing, sandbags, etc.)
  • Inconsistent lethality (clearly small arms lethality depends on shot placement, but the number of UK, US, and other soldiers, who report having needed to use multiple rounds to incapacitate an enemy, suggests that 5.56 mm may not be able to transfer its kinetic energy into targets as effectively as it was designed to do; this has to do with the bullet’s ability to yaw (tumble) consistently when it penetrates a target)
  • Insufficient suppressive effect (The sound and impact signature of 5.56 mm ammunition striking nearby does not always force enemies to react – often they will simply ignore it)

There has been much debate about the extent and true impact of perceived 5.56 mm ammunition deficiencies.

Whether concerns are real or imagined, it is probably fair to say that 5.56 mm is effective within its range envelope, i.e. under 300 metres.

With a clear need for dismounted infantry to engage targets with rifles to 600 metres and with machine guns to 800-1,000 metres, a number of armies have re-issued larger calibre 7.62 mm weapons to provide additional long-range firepower at section and platoon level.

These range requirements were standard British Army doctrine until we adopted 5.56 mm NATO ammunition.

The thinking behind a small calibre, high velocity calibre was that 90% of combat engagements would shown to occur at ranges under 300 metres. In Iraq and Afghanistan, the need to suppress enemies with small arms has required a capability to engage at ranges out to one kilometre.

Moreover, the adoption of x4 combat gun sights has made it much easier for soldiers to effectively engage targets at long distance.

The other reason why 5.56 mm ammunition was adopted was because 7.62 mm rounds were perceived to be too big and powerful for general purpose use.

With infantry units re-adopting 7.62 mm weapons, this has re-introduced a number of previous disadvantages:

  • Heavy weight (7.62 mm cartridges weigh twice as much as 5.56 mm ones)
  • Excessive recoil (a kick of 16 Joules for 7.62 mm versus 4 Joules for 5.56 mm)
  • Inefficient bullet design (a 7.62 mm projectile loses energy very quickly due to its stubby aerodynamic shape; therefore, it needs more energy to achieve long-range performance, thus it has greater recoil)
  • Over-penetration at short range (a 7.62 mm has so much energy that in CQB situations it can pass through several walls potentially causing collateral damage, or, where it hits a solid object, the risk of ricochet poses a danger to troops using it)
  • Reduced hit probability (put simply, the heavier a round is, the fewer you can carry. Troops equipped with 5.56 mm can carry double the amount of ammunition versus those equipped with 7.62 mm, therefore have a greater chance of hitting any given target)

The drawbacks of both ammunition types mean that neither can fully replace the other.

So NATO armies have generally adopted a dual calibre approach with 5.56 mm ammunition used in assault rifles and 7.62 mm ammunition used in machine guns.

The US Army’s 5.56 mm M855A1 EPR was meant to address many of the exiting issues with this calibre.

M855A1 Enhanced Performance Round
M855A1 Enhanced Performance Round

One problem it hasn’t solved is the need for longer range.

With the drawdown from Afghanistan proceeding more or less on schedule, there has been little pressure to change the status quo of the dual calibre small arms system that most NATO armies have now adopted.

This changed last year when the US discovered that various potential enemies have been quietly enhancing their own small arms capabilities and are on the verge of achieving overmatch.

There has been no specific information on what the evolved threat is, but it appears that the Chinese and Russians are about to field improved ranges of weapons and ammunition.

Given problems with the M855A1 EPR, the US Army needs a fix not only in the short-term, but also for the long-term.

More fundamentally, briefings at the recent NDIA event in New Jersey last week, suggest that both users and small arms weapon designers believe that 5.56 mm has reached the end of its development potential.

The confluence of these factors has forced the US Army to reconsider its future small arms needs. We therefore appear to have reached a major inflection point where NATO may once again consider a completely new and different small arms solution.

The 2014 CLAWS and LDAM programs

In early November 2013, at the US National Defence Industry Association (NDIA) symposium, held at Picatinny Arsenal, the US Army announced that it had initiated a new ‘Caliber Configuration Study’ to support two new programs:

CLAWS – Combat Lightweight Automatic Weapon System

This is envisioned to replace legacy weapons with a modular small arms system including a carbine, assault rifle, SDM/ DMR rifle and SAW / LMG.

Tt may also include a subcompact weapon. The requirement mandates that weapons should reconfigurable by the operator with interchangeable barrels, stocks, accessories, etc. All must be designed ‘within the art of the possible’, i.e. they should incorporate evolutionary technology, not revolutionary Star Wars technology.

The calibre is TBD from the pending CCS study.

LDAM – Lightweight Dismounted Automatic Machine-gun

Envisioned to replace the Medium Machine Gun and possibly the HMG (.50 BMG). This will be a weapon similar to the GD .338 Norma MMG, but calibre is again open and will be TBD from the CCS study.

The Caliber Configuration Study will consider exactly what calibre, velocity, mass of projectile, and projectile construction characteristics are required to achieve reliable performance across a range of combat scenarios, engagement types and ranges. It will build on the US ARDEC calibre evaluation study that was conducted prior to the IC competition.

This new initiative means we will see a proper industry-developed, army-endorsed and government-funded effort to produce an intermediate calibre military general purpose cartridge and portable heavy machine cartridge. Based on recent developments, we can expect the following calibres will be evaluated for CLAWS:

  • 6.35 / .250”
  • 6.5 / .260”
  • 6.86 / .270”
  • 7.0 / .280”

All projectiles will be lead free. All cartridge options will be convertible to polymer case options.

For LDAM, the requirement is less well-defined at this stage, but is expected to look at larger calibres along the following lines:

  • .338” / 8.59x70mm Lapua
  • .338” / 8.59x64mm Norma
  • .354” / 9x90mm MEN
  • .416 / 10.6x83mm Barrett

A range of ammunition types will be evaluated including AP, anti-personnel and incendiary. All cartridge options will be convertible to polymer case options.

The most important potential outcome is that the US may again unilaterally adopt a new and different cartridge to the rest of NATO. If it does, a standardisation competition would more than likely be held to align usage of the new calibre among non-US alliance members, just as we did with 5.56x45mm in 1979.

We don’t know the exact timeline, largely because it hasn’t been decided yet; however, the CLAWS program represents a clear admission that 5.56 mm has reached the limit of its development possibilities, that M855A1 is untenable, and that a longer range requirement is needed – something that the rest of NATO has refused to admit.

To overcome potential negative criticisms about M855A1, the USA will be keen to expedite selection and procurement of a replacement.

As things stand, the armies of the USA, Canada, UK, Germany, and France are all now on a critical path to replace their small arms between 2020 and 2025. In procurement terms this is tomorrow.

US Army estimates suggest that it will take 18-24 months to select a calibre and a further 60 months to develop, test and validate prototypes, leading to a final recommendation. Needless to say that industry is already working in support of this by developing a range of potential intermediate calibre proposals.

The 6.8x43mm Remington SPC was recently adopted by Jordan and Saudi Arabia, which between them have bought 40,000 guns.

LWRC Six8 Carbine in 6.8x43mm Remington SPC, recently acquired by Saudi Arabia and Jordan
LWRC Six8 Carbine in 6.8x43mm Remington SPC, recently acquired by Saudi Arabia and Jordan

They gave Federal ATK $20 million to perfect the ammunition and $100 million contract to LWRC to build an M4 clone in 6.8mm. While the 6.8×43 Remington SPC has been seen by many as potential replacement for 5.56 mm NATO, it offers good terminal effectiveness (lethality) but is still only a 300 metres calibre.

Another recent intermediate calibre that has also drawn much attention is the 6.5x39mm Grendel.

This offers excellent long-range performance that comes close to matching 7.62mm NATO thanks to a long aerodynamic bullet that retains energy better than any existing military design.

But since it has not yet been optimised for military use against human targets, the projectile does not yet provide reliable terminal effectiveness at short range. With a slightly longer cartridge providing increased power, there is no reason why this round couldn’t provide the performance characteristics the US Army is looking for.

Ammunition types (left to right) 7.62x51mm NATO, 6.5x43mm intermediate calibre prototype, 6.5x39mm Grendel, 6.8x43mm Remington SPC, and 5.56x45mm NATO
Ammunition types (left to right) 7.62x51mm NATO, 6.5x43mm intermediate calibre prototype, 6.5x39mm Grendel, 6.8x43mm Remington SPC, and 5.56x45mm NATO

Both 6.5mm Grendel and 6.8mm Remington SPC rounds are designed to fit within the action length of 5.56 mm weapons (58 mm). This limits their long range performance.

For example, you could not fit the necessary amount of propellant and a tracer projectile in a Grendel case.

In short, neither round is suitable for military applications without further development, but both are a good start point.

Four weapon types should result from the CLAWs program as follows:

  1. Carbine with 12-13″ barrel
  2. Assault rifle with 16″ barrel
  3. DMR /LSW with 20″ barrel and bipod
  4. Belt-fed LMG with 20-24″ barrel and bipod

If this seems similar to XM8, it’s because a key system requirement is modularity. A sub-carbine could be a separate PDW in a different calibre. The squad-level machine gun would obviously be able to be mounted on vehicles to replace 7.62 mm machines, which is why a belt-feed mechanism is preferred, but this probably won’t happen initially.

In terms of LDAM, it is worth mentioning that a polymer .338 round weighs close to brass case 7.62 mm round. The GD .338 Norma MMG weighs close to an M240.

So you could get a man-portable heavy machine gun that matches .50 Cal in a package close to the weight of legacy GPMGs. That has to be good news for dismounted infantry operating on foot in difficult terrain. This weapon would most likely become a standard vehicle-mounted and co-axial machine gun on AFVs.

In essence then, CLAWS is a program to replace 5.56 mm NATO and LDAM is a program to replace 7.62 mm NATO. It isn’t clear where this leaves .50 Cal.

Given the excellent performance of .338 as a sniper calibre in Afghanistan, it seems the best option to become the new HMG calibre, but that doesn’t mean that .50 Cal will be retired any time soon – certainly not before a general purpose .388 round optimised for use in machine guns has proved itself in combat.

And it isn’t clear whether the form factor will be Norma or Lapua.

Given that the installed base of .338 Lapua is greater than that of Norma, NATO might prefer to standardise on the Lapua round’s dimensions. But if the USA deems the Norma round to be preferable, the UK may have to change its L115A3 .338 sniper rifles, since it wouldn’t make sense to have two different types of .338 round in service.

In addition to .338 machine guns and bolt-action sniper rifles, we are also likely to see semi-automatic .338 designated marksman rifles make an appearance.

Noreen .338 Lapua semi-automatic DMR weighs 11.2 lbs. / 5 kg

Any .338 weapons that are selected are likely to be held at company- or platoon- level, not at squad level. Squads are likely to standardise around a single CLAWS calibre, whatever is selected. This should result in a single family of weapons, simplifying procurement, training and battlefield re-supply. Spare parts and fleet maintenance costs should also be reduced. Most important of all, all squad members will be able to engage enemy targets at both short- and long-range.

Rifleman are likely to carry a standard assault rifle configuration with something like a 16.5” barrel. Special Forces, radio operators and grenadiers are likely to carry a carbine version with 12-14” barrel.


It makes no sense to replace our small arms inventories now – not unless we foresee ourselves becoming embroiled in a major international conflict within the next five years.

The controversial nature of Iraq and Afghanistan means that we’re likely to avoid getting involved in a situation unless we absolutely have to. The UK parliament’s reluctance to commit UK forces to the Syrian situation illustrates our new found foreign policy conservatism.

Given that so many other governments are also looking for cost savings, armies will be encouraged to postpone major new programmes for as long as possible. By 2020, however, the global economy should be back on track.

The time between now and then can be usefully employed to consider and develop exactly what we need for the next generation.

The UK’s SA80 weapon system will be 40 years old and extremely worn out. If we can align ourselves with what the US Army is doing, we should be able to adopt an ideal range of infantry small arms that give us a range of flexible capabilities across a wide range of deployment types.

As things stand, it looks very likely that the USA will ‘encourage’ more than force the rest of NATO to change small arms calibres. While few NATO allies will wish to admit their concerns with existing ammunition types, they will welcome any solution that provides clear advantages over legacy weapons.

And, if America is developing an ideal small arms system that its allies can use, it will have saved them the development costs.

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