NATO and the Next Generation Squad Weapon- NGSW

The 6.8mm Elephant in the Room

The United States Army has made the biggest change in a generation to its small arms fleets by replacing its standard infantry rifle (the M4) and Light Machine Gun (SAW) with a ‘Next Generation Squad Weapon‘ (NGSW) multi-calibre system based on a new 6.8mm round with high-performance technology to be more lethal at greater range. Some NATO governments are scratching their heads about what this means for the bedrock of NATO interoperability.

This decision butts up against three important contextual factors:

1. More than two years of war in Ukraine has seen an unprecedented focus on the Russian threat and subsequent multi-lateral gifting programmes to arm Ukraine, and emergency NATO memberships for Sweden and Finland.
2. The 5.56mm ‘SS109’ round has been the cornerstone of NATO interoperability since 1980, when it was adopted by most NATO countries, while a few influential members have recently procured new 5.56 assault rifles including France, Germany, the Netherlands and the UK.
3. Since the drawdown in Afghanistan, there has been a growing movement questioning the effectiveness of 5.56 on the modern battlefield.

Putting aside the classified details of the original US Army requirement for the Next Generation Squad Weapon (NGSW) programme, the Americans took a logical approach: start with the threat (the target) and work back to the weapon (the ammunition) and finally the delivery platform (the rifle/gun). This may sound obvious, but the reality is this approach is truly not the norm for military small arms procurement with NATO governments for a variety of reasons. It is commonplace for the choice of ammunition nature not to be central to the requirements simply because in-service ammunition natures have a very long service life – it is hard to change them.

This article explores the major implications of the US Army’s NGSW programme to future NATO small arms procurements to both dispel some myths and assist the NATO community in understanding the situation and the NGSW.

Show us the money!

In 2017, Lt Gen Mick Bednarek testified on the issue of what happens when a 5.56 round hits someone with body armour to a Senate Armed Services Committee Hearing on small arms (Verger, 2024):

• “The US is facing adversaries with L2-3 body armour that precludes our lethality…regardless of range.”
• “Our capability to eliminate this threat at medium or long range is almost gone, so we must have small arms systems that can stop and can penetrate that increased enemy protection.”
• “I think the US Army universally realizes that the 5.56 bullet can’t defeat Russian body armor.”

In the same article, Col Jason Bohannan (Programme Executive Office [PEO] Soldier, US DoD) is quoted referring to the NGSW programme:

“…people get myopically focused on body armor…but there’s a series of target sets in the battlefield that will exist for 10 years. And we’re trying to balance all of that to put [the] US Army [and the DoD] at large, in an advantageous position.”

Fast forward to 2022 when the US Army determined the old standard to be inadequate for the modern battlefield and disrupted the foundation of NATO interoperability by introducing two new squad weapons based on a new ammunition cartridge.

Before we get into the detail here is a big caveat up front – the US 6.8mm GP projectile ¹ (the XM1186) is owned by the US Department of Defence, while the hybrid case – the key component to achieving the high velocity that delivers the lethal punch for the NGSW- is owned by American producer SIG Sauer Inc. Therefore, if NATO governments want to know specifically what this projectile does, they should dust off their bi-lateral defence sharing agreements and speak to their US counterparts; but the capability behind NGSW comes from the hybrid cartridge. The SIG Sauer hybrid high performance cartridge is a lighter brass-steel composite that allows increased loads and delivers approximately 20-25% more barrel pressure and therefore muzzle velocity, which translates to better ballistic performance, greater penetration at longer range for a given projectile.

It is logical to assume that not much is going to happen elsewhere in NATO until partners are ‘shown the money’ behind the NGSW requirement. Changing NATO standard ammunition natures is at the very heart of interoperability and so there is a very large elephant-sized challenge in NATO regarding both ratifying a new ammunition standard, and then individual nations adopting it.

Herein lies the problem that 6.8 raises the issue of understanding… NATO’s comprehension of what their in-service ammunition actually does, and more importantly, does not do. Given the relentless churn of staff officers and tightening budgets, and lack of experts in technical agencies; detailed ballistic expertise in most NATO defence departments lies with a small number of people in each nation, and they are typically not procurement decision makers.

Intermediate calibre cartridges such as the 6.8 are not new. In fact, one of the bullet designs proposed by the UK MoD before NATO 5.56 adoption was a .276” (7mm) calibre bullet. As Ford documents in Weapon of Choice (2017, Chapter 3), this proposed 7mm round fell foul of many years of NATO politics and was ultimately assigned to history. There is one lesson to draw from this, though – politics trumps evidence in defence procurement.

It’s not just about the calibre

The calibre debate is a bit hackneyed in military circles because it is usually shrouded in a fog of misinformation, subjective industrial marketing and ego. Anyone who enters the calibre debate sounds like an expert. Moreover, I’ll let you into a secret – firearms and ammunition companies will do their best to sell firearms and ammunition and, therefore, fuel the debate. There is of course merit to having an informed debate occasionally – like now, but strictly speaking a debate on calibre is missing the point.

The main problem with the calibre debate is that it almost always focuses on a single dimension (diameter), as if that dimension summarises the complexity of ammunition natures and delivery systems without any further detail. 6.8 is 6.8 is 6.8 – it’s not that simple.

Talking about a bullet calibre in isolation is like describing road vehicles by the number of wheels

Using this criterion, a Humvee could be confused for a Mini.

What is not usually discussed in detail are the many other engineering factors that govern bullet-target interactions: bullet design, velocity, spin rate, ballistic coefficient, barrel twist, energy, wound ballistics etc.; these are all the hallmarks of SIG hybrid case technology at the centre of the NGSW system. Lest we forget the often neglected but critical external factors: through-life sustainment, training, environment, human factors and more.

In 1980 a ‘standard’ NATO SS109 (dual core steel tip lead rear) 5.56x45mm bullet was adopted by NATO (~4g mass at 930m/s, 1730J muzzle energy). The NATO specification for this round is to penetrate a 3.5mm mild steel plate at 570m. While 7.62x51mm (~9.5g, 830m/s, 3270J muzzle energy) respectively must penetrate the same target at 550m (NATO AEP-97, 2020). Unsurprisingly, this pre-1980s Belgian design for 5.56 did not include the requirement to penetrate L4 body armour, likely because ceramic composites were not widely available then. It is therefore a simple logical step to conclude that these 40+ year old armour standards are not reflective of modern widely available protective systems, and therefore our rounds of yesteryear do not defeat peer adversary wars of today.

It is worth noting that at time of introduction some of the perceived advantages of the SS109, when compared to the 7.62x51mm concurrently used by many nations, were human factors centric i.e. reduced cartridge mass and with it soldier load and recoil.

By any measure and configuration, a standard 5.56mm Full Metal Jacket (FMJ) bullet (1276 ft/lbs or 1730J muzzle energy) delivered from a conventional cartridge is a relatively small round for personnel targets, while hunting legislation offers a window as to why. In the UK the minimum requirement for a round to hunt the four larger resident deer species is a .240” calibre, soft/hollow-nosed bullet with at least 1700 ft/lbs (2305J) of muzzle energy (Deer Initiative, 2009). In practical terms this equates to use of a minimum of a 6.5mm (.243”) round for legal hunting.² So, take a medium size male deer (Fallow or White Tail) at an average of 70-80kg at middle age – a .243” or .308” (7.62x51mm) will do nicely, but a 5.56mm bullet does not have sufficient energy to humanely dispatch it; yet it is legal for use in armed conflict against a 70-90kg person. Under UK law, 5.56 bullets are insufficiently lethal to dispatch deer of comparable size to humans; and deer don’t wear body armour.

There are however many scientific problems with trying to describe the comparative potential of a projectile to wound with simple metrics such as calibre, energy, bullet structure, hit probability – but the need endures for such metrics to make the distinction between effect and effectiveness, which should be the basis for coherent capability decisions.

“The effect of a bullet depends on a wide variety of factors that extend well beyond design characteristics. In the first place a bullet needs to strike a certain part of the body. However, the ability to realise this potential reality depends on the particular climatic and other circumstances on the day as well as the skill at arms of the shooter.”(Ford, 2017)

Ford gives a comprehensive history behind various energetic rules-of-thumb such as the 58ft/lbs (80 Joules) criterion used by experts over the years (Ford, 2017, Chapter 4) if you’re interested, and equally sound reasons why these metrics individually fall short of being universally useful. Other references cite 200 Joules as the energy necessary to incapacitate a human target (Cranfield, 2013). Like calibre, using only round energy to describe lethal effect falls short of being useful by itself.

If soldiers need to defeat enemies wearing NIJ³ level 4 body armour⁴ at a range of 300-400m, then your standard SS109 is not going to do it, unless you hit them in the central nervous system – half of which is covered by armour. NIJ Level 4 is the benchmark for COTS military SAPI⁵ hard armour plates that are generically rated to stop everything below 7.62mm Armour Piercing (AP) rounds – note projectile construction also makes a difference. Moreover, most NATO militaries restrict conventional users to FMJ bullets for legal reasons, which are not optimised to transfer their energy rapidly unlike other projectile designs.

Suffice to say, the science of wound ballistics and protective systems performance are important fields of evidence in understanding lethality, but they are fiendishly complex and not universally understood, but this is a rabbit hole not for now. One essential approach for intelligent procurement is understanding the wider system and use cases of an intended capability – a major part of which is wound ballistics, which certainly cannot be summarized well by single metrics.

A system of systems

The foundation of the NGSW programme was a robust technical systems analysis of the kill chain from target to soldier. The US Army started with a requirement to provide overmatch capabilities to defeat peer and near-peer level body armour and designed a bullet to do so at a given energy level – because that would be analytically sound. It’s not just about penetrating body armour, there are other benefits to having a larger, faster round – principally being able engage enemies beyond 600m with reliable consistency. For this you need more than just a new round; you also need a precise weapon system that helps reduce the errors inherent in shooting at longer ranges i.e. range estimation, bullet drop and shooter stability.

The whole point of NGSW is to keep the superior numbers of a peer enemy at the extreme edge of their range.

A PEO Soldier spokesperson outlined the NGSW systems view:

“The decision to settle upon a 6.8mm round resulted from extensive testing and research by Army laboratories, which closely examined factors such as threats, target sets, weight, performance, and controllability. However, it’s important to note that any changes in ammunition would require adjustments in other areas as well, such as weapon design and soldier training.” (Adde, 2019).

In the same vein, the UK MoD systems view of lethality in Figure 1 below, offers a logical framework that could illustrate the NGSW system of systems – defining the kill chain to shape holistic requirements.

Figure 1 demonstrates the wider system elements of lethality that affect a soldiers’ ability to deliver a lethal effect on target including sensing, decision-making, target engagement, effect, and feedback. It shows how different factors affect different parts of the system. Weapons and ammunition are only parts of the kill chain.

In 2015 a NATO Weapon and Sensors brief by the Swedish representative (Per Arvidsson) stated that ‘there is nothing wrong with 5.56!’ and concluded that training standards, education and perception of ballistic terminal effect were lacking amongst conventional military communities (Arvidsson, 2015). Per was right, if you take the view of someone who understands in detail what 5.56 does; and you are content with your weapon performance against your target set (at the time). It is well-known that many professional armies do not adequately teach their soldiers about ballistic performance limitations in detail. Moreover, the Swedish study was conducted at the tail end of the Counter-insurgency wars in Iraq and Afghanistan, not the peer threats of today and tomorrow.

There are clearly arguments for both sides, but if you don’t understand what your equipment does in the context of a system, then how do you know if it is doing what you need it to do?

What about Training?

In 2016 Stewart and Lowe (2017) conducted an in-depth analysis of British Army live fire tactical training, demonstrating the considerable deleterious effect of battlefield conditions on hit probability – “there is an 80% reduction in performance between shooting on ranges and field firing.”

Data from some studies also suggests that most historical infantry engagements happen at <300m (Ehrhart 2009). While this is ‘known’ by most NATO countries, there is always the creeping temptation to define requirements asking for performance at greater ranges, irrespective of ballistic limitations – after all if you can hit your enemy further away then you have an advantage.

Thomas Ehrhart arrived at similar conclusions in a monograph that combines historical analysis and personal experience – “…a general lack of emphasis on appropriate small arms doctrine, written by subject matter experts, has resulted in poorly trained soldiers and leaders.”

Furthermore, by way of tangential corroboration using historical analysis, Murray (2013) provides an insight using historical research of combat indicating that even participation rates (willingness to engage) of infantry in major combat operations may be as low as 15%.

From these few pieces of research, we could surmise two things with some confidence – 1) small arms lethality in NATO governments is not well understood by most, and 2) there are a myriad of factors that contribute to the gap between effect and effectiveness at the heart of which are some important human factors – training, psychology and education.

The weapon at the heart of NGSW

In many ways 6.8mm is a red herring, because calibre is at best a metric of overstated importance. The hybrid cartridge capability is the bit that makes the projectile go faster and further – this is driving force behind the weapon system – the hybrid cartridge is the weapon in the weapon system.

The US Army chose a more demanding defeat requirement (energy and range) than 5.56, and therefore the bullets had to be bigger, delivered with more energy, and so the cartridge had to be enhanced and the delivery platform more robust to handle the engineering stresses. More ballistic energy requires more mass in the system:

Until the technology fundamentally changes, physics will not give you bigger bullets with more energy at longer range from rifles that are lighter and smaller.

The technology that drives the 6.8 cartridge is the SIG Sauer hybrid high performance cartridge that delivers approximately 20-25% more barrel pressure and therefore increased muzzle velocity. The SIG Sauer 6.8 commercial variant – the .277 Fury, propels a 140-grain bullet at 2950 feet per second (900+m/s), providing it with 2,706 ft/lbs (3668J) of muzzle energy (Witner, 2024). That equates to pushing a bullet with more than twice the mass of a 5.56, at similar velocities, creating more than twice the energy.

To show the difference a hybrid case makes Figure 2 below shows comparative performance data for the same (US) M80/M80A1 7.62x51mm projectiles fired from the same rifle but with both conventional brass and hybrid cases.

The benefits of hybrid case technology vs. conventional cases are clear in Figure 2 – more penetration at longer ranges with less drop and for a lighter case. The hybrid cartridge means the difference between target penetration and no penetration for an M80A1 conventional cartridge beyond 200m – see the effect on 9.5mm of vehicle armour (top left Figure 2). Moreover, the comparison graphs (bottom) show increased velocity (A & C) and reduced dispersion (B & D) comparing high performance natures with a standard M80/A1 cartridge (grey).

It’s not about 6.8mm. The Next Gen weapon at the heart of NGSW is the hybrid high performance cartridge.

So what about the platforms?

The MCX Spear⁶is a user/mission-configurable suppressor-optimised rifle platform that weighs 8.4lbs/3.81kg unloaded (South, 2024) which is capable of delivering 6.5, 6.8 and 7.62mm high performance and conventional ammunition natures with sufficient energy to defeat peer adversary targets out to 600m. It is based on the SIG Sauer MCX family used by numerous elite forces globally – known for multiple mission configurability and modularity.

During initial fielding with the US Army 506^th Infantry Regiment and the 101^st Airborne Division, Colonel Trevor Voelkel (1^st Brigade Commander) said this of the XM7’s terminal effect (South, 2024):

“Seeing the effects we had on the targets makes up for any concerns I had initially about the increased weight.”

The M249 replacement is the SIG Sauer LMG⁷ which is a multi-calibre user/ mission-configurable suppressor-optimised rifle capable of delivering 6.8mm and 7.62mm high performance and conventional ammunition with sufficient energy to defeat peer adversary targets out to 800m. At 13lbs/5.9kgs it is one of the lightest squad level belt-fed machine gun in the world, lighter than an M249 SAW at 9.3kgs unloaded.⁸

The core of the XM7 and XM250 capabilities are increased lethality, extended range, user configurability, proven quality and extensive DoD testing.

Conclusion

NGSW is changing the NATO lethality landscape and in so doing the US Army has changed a basic building block of NATO interoperability.

With a shortage of lethality technical experts, it would be prudent for NATO defence departments to seek answers to better understand the details behind the US Army’s requirements in order to be fully informed when making future procurement decisions. Users and procurers alike should start with a good look at the targets and work back i.e. energy delivered to a specified target set, analysis of wound ballistics, and accuracy and consistency at range, as the performance criteria is what matters most. All other requirements, including the often neglected but important human factors, flow from this.

If after doing this analysis and staring long at the 6.8 elephant in the room, a government may still be content with the performance of its 5.56mm round, then why would it make a change? If, however, partner nations conclude their standard ammunition natures do not defeat the most dangerous (or even most likely) threats they likely need to fight, then it is time to do something:

• Define the target(s) and what energy, consistency and range you need – define the Use Case(s).
• Work back from the bullet – look at the projectile and cartridge options to match the Use Case(s).
• Define your requirements and share with partners to align common requirement sets.
• Conduct an options analysis: cost the requirement options and balance the cost-benefit with your Equipment Programme against the prevailing contextual threats and operating concepts.

Don’t just procure a new rifle, then think about your ammunition later, because hastily procuring another 5.56 rifle without robust requirements definition could be a 40-year investment in 1980s technology.

Of course, you always have the option to do nothing – a bit of masterly inactivity.

1. N.B. It is US DoD Government Furnished equipment subject to a classification.
2. Muntjac and Chinese Water deer are a variation on this rule of thumb due to their small size – minimum .220” and 1000 ft/lbs energy required.
3. US National Institute of Justice.
4. US National Institute of Justice (NIJ) classification for body amour products capable of protecting against common NATO ammunition natures.
5. Small Arms Plate Insert.
6. US Army designation XM7.
7. US Army designation XM250.
8. odin.tradoc.army.mil.