By Nicholas Drummond

Building on Rexer’s previous article on this topic, this piece considers the need for a modern day version of the classic assault gun and envisions what a British Army Mobile Gun System might be like. The author would like to sincerely thank Ogden Dowcett for all his hard work in developing and rendering the Boxer MGS 3D concepts that follow.

Disclaimer: This article was not sponsored or endorsed by Rheinmetall, BAE System, Krauss-Maffei Wegmann., John Cockerill Defence, and OTO-Melara. It is an independent view designed to generate interest and discussion.

Above: Boxer MGS proposal with John Cockerill Defence 30105 105 mm gun turret. (Image: John Cockerill Defence)

Contents

01. Introduction
02. Evolution of WW2 assault guns to modern day mobile gun systems
03. Are the characteristics of 20th Century assault guns relevant today?
04. Envisioning a contemporary UK Assault Gun
05. Conclusion

01. Introduction

During the Second World War, Allied and Axis assault guns delivered an effect out of all proportion to their cost and complexity. They were simple and inexpensive to produce relative to tanks. They were easy to operate and versatile in role. Engaging in close infantry support and anti-tank tasks, they were suitable for both offensive and defensive operations. For all their benefits, however, few assault gun designs were ideal. They lacked protection and even turrets. They were the product of desperate times and should not have been as effective as historical accounts suggest they were. 

Above: The M3 half-track was used as the basis for the T30 Howitzer Motor Carriage. This was a first US attempt to create a “no frills” assault gun for infantry units.

After 1945, as postwar armies reverted to smaller peacetime structures, assault guns fell out of favour despite their success in battle. The reason was a large number of a surplus tanks. The best ones were retained, meaning that armies could rely on a single tank type to fulfil multiple roles, including main battle tank, assault gun and tank destroyer.

Today, many NATO armies are in the process of replacing old and worn out AFVs, some of which have been in service since the early 1980s. The increased sophistication of modern MBTs and resulting higher costs have limited the number of new platforms that can be afforded. Secondly, the need for rapidly deployable medium weight forces has seen the emergence of a new class of 8×8 wheeled armoured vehicle that can perform expeditionary missions in faraway places where it is difficult to deploy tanks. The need to support mobile infantry units has led to several armies developing direct fire platforms capable of mounting 105 mm or 120 mm guns. More recently, the US Army has announced plans to field a tracked Mobile Protected Firepower (MPF) platform with a 105 mm gun to support Infantry Brigade Combat Teams (IBCTs). It is difficult to see these and similar vehicles as anything other than modern interpretations of the classic WW2 assault gun. 

Are these vehicles merely the product of reduced budgets and do they offer only limited utility? Or has the time come to think more widely about a new class of less expensive assault guns and tank destroyers? If so, how should such a vehicle be configured and used? Does it even need a large gun, or could the same effect be achieved by mounting a mix of antis-tank missiles and anti-structure rockets? This article will try and address these questions and propose a range of potential solutions. 

02. Evolution of WW2 assault guns to modern day mobile gun systems

During the mid-1930s, as Nazi Germany was refining its Blitzkrieg tactics and ramping-up production of its new Panzer divisions, a Wehrmacht general, Erich Von Manstein, identified the need for a low-cost assault gun that would provide close infantry support. Based on his First World War experience, Von Manstein believed that an armoured vehicle capable of providing direct HE fire to eliminate bunkers and machine gun nests would increase the effectiveness of troops engaged in ground assaults. In 1936, two German firms, Daimler-Benz and Alkett, were tasked with developing and manufacturing a new Sturmartillerie (assault artillery) vehicle. Using the chassis and driveline of the Panzer III, the turret was dispensed with to create a simplified platform that mounted a low-velocity 7.5 cm StuK. 37 L/24 cannon in a compact casemate. This gave what was called the Sturmgeschütz a low silhouette, making it easy to conceal as well simple to produce and support. The newly formed Panzer divisions were skeptical about the concept, so it was decided that the new vehicles would be an artillery asset. First used during the Battle of France, the Sturmgeschütz  or StuG III immediately proved its worth. Lighter than turreted tanks, it was compact and agile, yet capable of delivering a decisive effect. 

Above: The Sturmgeschütz IIIG assault gun was the most prolific assault gun of WW2. Initially used to provide fire support for attacking infantry units, later, it was employed defensively as a tank destroyer. It excelled in both roles.

By the time Hitler invaded Russia, the StuG III had become an organic part of the Panzer divsions.  When the tide started to turn against Germany, instead of being used for assault, the StuG III was used defensively. Experience saw various improvements made. The Ausf. F was significant in that it mounted a longer and more powerful 7.5 cm StuK 40 L/43 gun. In addition to high explosive ammunition, it could also fire armoured-piercing rounds capable of penetrating 91 mm of RHA steel at 500 metres – enough to defeat most Allied tanks of the period. However, the definitive StuG III version was the Ausf. G, which was the most widely produced mark. By the end of WW2, 10,086 StuG IIIs had been produced, making it the most prolific Axis “tank” type. According to the Bovington Tank Museum, StuG IIIs accounted for 30,000 allied tanks destroyed. Considering how much simpler its design was versus the Panzer III and IV, lacking a turret and needing to be slewed on its tracks to aim its gun, its success in battle made it emblematic for this AFV type. 

The United States Army also identified the need for a tank destroyer that was agile, versatile and lethal. Its first attempt to produce one was a 57 mm gun mounted on an M3 half-track, the T30 Howitzer Motor Carriage. In November 1941, a dedicated tracked tank destroyer platform was requested. This was developed during early 1942 with deliveries starting as soon as June of the same year. The result was the M10 Wolverine. This mounted a 3-inch (76.2 mm) Gun M7 in a rotating open-top turret on a modified M4A2 Sherman tank chassis. Like the StuG III when it was used defensively, the M10’s job was to stop armoured breakthroughs. To make it sprightly, it had thinner armour, but it wasn’t much faster or more manoeuvrable than a standard M4 Sherman. The M10 was later replaced by the M36 Jackson, which mounted a more powerful 90 mm gun. 

Above: The M18 Hellcat tank destroyer – the fastest tracked combat vehicle of WW2. Despite primarily being used as a tank destroyer, its ability to fire HE as well as AP ammunition meant it could also be used as an assault gun.

Perhaps the most impressive US tank destroyer of WW2 was the M18 Hellcat. This mounted the same 76.2 mm M1A2 gun of the M10 on a bespoke lightweight 16-tonne chassis. Again employing a rotating open-top turret, this vehicle was extremely compact and highly mobile. In fact, it was the fastest “tank” of the Second World War with a top speed in excess of 50 mph. During Patton’s thrust into Germany, Hellcats proved adept at defeating enemy counter-attacks. As well as firing anti-tank rounds, all US Army tank destroyer types (M10, M36 and M18) could fire HE ammunition, enabling them to be used as assault guns for supporting infantry. 

In comparing the Sturmgeschütz III and the M18 Hellcat what is interesting is that the Sturmgeschütz was an assault gun that was later used as a tank destroyer, while the M18 Hellcat was a tank destroyer that was later used as an assault gun. This suggests that the terms assault gun and tank destroyer are interchangeable. Today, this type of vehicle is often described as a Mobile Gun System. They are also considered by some to be light or medium tanks, but actually light tanks are primarily designed for reconnaissance roles.

Although the British Army used American tank destroyers, the UK did not develop a specific vehicle of this type until late in the war. Instead, it relied on an alternative doctrine based on two different tank classes. Heavier protected tanks, such as the Matilda II and Churchill, were used as “Infantry” tanks. Large and slow, these would accompany assaulting infantry to provide close support in the same way that German assault guns were used. If they encountered enemy tanks, then their 6-pounder or 75 mm guns would engage them using AP ammunition instead of HE. Britain’s other class of tank was the “Cruiser” tank. Designed to be lighter and therefore faster and more nimble, these were used for armoured thrusts. It was not until 1943 that Britain developed a dedicated tank destroyer when it produced the Archer 17-Pounder Self-Propelled Anti-tank Gun. Overall, Allied assault gun doctrines were less well conceived than those employed by the Wehrmacht.

Britain introduced the Centurion tank just as the war ended in 1945. It was categorised as a “Universal” tank and presaged what we now call the “Main Battle Tank.” With the arrival of other postwar MBTs (including the Centurion, M-47/ M-48 and M-60, Leopard 1, AMX30, T-54/ 55, and T-62), assault gun/ tank destroyers were mostly retired without replacement. One exception was Germany’s Kanonenjagdpanzer 90. This used the M47 Patton tank chassis as a basis for a tank destroyer platform with a 90 mm gun. By the time Soviet Army fielded the T-64 and T-72 MBTs, it was obsolete and the fleet was converted to fire ATGMs before being retired at the end of the Cold War. The only other postwar design that came closest to the brutal simplicity of a WW2 assault gun was the Swedish S-Tank. Although it looked like a tank destroyer, it was very much a main battle tank. 

Above: The UK Saladin and Saracen 6×6 family used a common drivetrain to create two distinctly different vehicles by swapping the front end with the rear. It was a simple but effective engineering solution to configure each vehicle according to its role.

In the 1950s, Britain introduced a new 6×6 wheeled family, the Saladin armoured car and Saracen armoured personnel carrier. Though not strictly an assault gun, the Saladin mounted a 76 mm gun that fired both AP and HE ammunition. This was considered ideal for supporting infantry in an assault gun role, but was primarily used for reconnaissance. In many ways, Saladin and Saracen previewed the medium weight concept we have today, but there was no major conflict against a peer adversary that ever tested how these vehicles would have been employed in combined arms formations. Instead, both tended to be used separately until they were replaced by the CVR(T) family in the 1970s. By this time, the focus was very much on divisional reconnaissance within a British Army of the Rhine context. It wasn’t long before the CVR(T) Scorpion’s 76 mm gun was superseded by the CVR(T) Scimitar’s 30 mm RARDEN cannon. 

Another postwar light tank/ recognisance vehicle that deserves a mention is the US Army’s M8551 Sheridan. This was a light and agile platform that weighed 15.2 tonnes making it suitable for air-dropping. It was equipped with a 152 mm gun launcher that could fire MGM-51 Shillelagh anti-tank missiles as well as HE rounds. It was not an ideal system and early issues with the missile meant that only eight out of many thousands of ATGM manufactured were ever actually fired in combat. Used in Vietnam, the Sheridan lacked protection and was vulnerable to heavy machine gun fire, RPGs and mines. 

Above: A soldier from 73rd Airborne Armor Regt., 82nd Airborne Division, prepares ammunition for an M-551 Sheridan light tank prior to operations during Operation Desert Shield.

As the Cold War drew to a close in the late 1980s, it was realised that most NATO reconnaissance vehicles lacked the protection needed to survive against Soviet IFVs, let alone MBTs. Britain’s CVR(T) had aluminium armour that could easily be penetrated by 14.5 mm machine gun rounds. It should be no surprise that its intended replacement, Ajax, has become a 43-tonne beast with Level VI+ protection and a 40 mm CT cannon.

By 1990, the universal adoption of IFVs meant that any notion of infantry still needing their own separate assault gun for close support was redundant. However, Germany, which had already switched to an 8×8 wheeled platform for reconnaissance tasks, the Luchs, decided that a wheeled assault gun / tank destroyer was worth exploring. It started to develop the 8×8 Radpanzer 90, which mounted the Leopard 1A3’s 105 mm gun turret on a new Daimler-Benz chassis. Although the prototype showed considerable promise, funding was cut post-1990. Despite not reaching fruition, the Radpanzer programme inspired the South African Army, which developed the Rooikat assault gun for use in various bush wars. It remains in service to this day. 

Above: Ahead of its time? The Radpanzer 90 was developed in the late 1980s, just as the Cold War was ending. Using a specially designed Daimler-Benz driveline and chassis, it was a highly innovative vehicle that mounted the Leopard !’s 105 mm gun turret to deliver extraordinary firepower in a compact and agile package – just like its tank destroyer forbears. Although the project was cancelled, the Radpanzer 90 inspired the South African Rooikat MGS and Italy’s Centauro MGS.

Also in the early 1990s, Italy shared Germany’s point of view about the potential for wheeled assault guns and developed a reconnaissance vehicle that also used the Leopard 1 MBTs L/52 105 mm gun, the Centauro. Weighing 24 tonnes with a power to weight ratio of 19.4 bhp per tonne, it was well protected enough to withstand 14.5 mm heavy machine gun fire all-round, while appliqué armour increased protection so that the vehicle could resist 30 mm rounds across the frontal arc. 

In 1998, the US Army developed the medium weight concept as we know it today. It fielded a comprehensive family of vehicles based on the LAV III platform including a 105 mm mobile gun system (MGS) that was conceptually identical to Italy’s Centauro. Intended to support infantry units in 8×8 Stryker M1126 Infantry Carrier Vehicles, the Stryker M1128 MGS is a classic assault gun and shows that the concept is far from an evolutionary cut de sac. 

03. Are the characteristics of 20th Century assault guns relevant today?

To understand the utility provided by mobile gun systems in a contemporary context, it may be helpful to summarise the characteristics of 20th Century assault guns and tank destroyers. The many benefits can be summarised by six common characteristics:

  1. Compact firepower. The overriding requirement was to mount the largest possible gun on the smallest possible platform. 
  2. Mobility. The most successful assault guns were much lighter and more agile than equivalent tanks that mounted the same gun. This meant that they could react faster to intercept an enemy flanking attack or unexpected manoeuvre. 
  3. Flexibility.  The ability to redeploy tank destroyers as the tactical situation evolved meant that they were highly flexible. Also, they could switch between attack and defence with ease. 
  4. Simplicity. Ease of production and operation were paramount. Most WW2 assault guns did not have turrets, or, if they did, these had open tops. A reduced weight also put less strain on the drivetrain reducing breakdowns. However, money was invested where needed. The StuG III, for example, had better optics than the Panzer III and Panzer IV.
  5. Ease of support. With the StuG. III based closely on the Panzer III, spare parts were plentiful, so it was easy to maintain. Without a complex turret, German assault guns were easier to repair if hit.  
  6. Affordability. Most assault gun types were 20-30% cheaper than equivalent turreted tanks.  

Does the concept still have merit?

The US Army’s Stryker M1128 MGS, Italy’s Centauro 2, and Japan’s Type-16 MCV all seem to follow the above formula closely. First and foremost, they mount large guns, either 105 mm or 120 mm, usually found on main battle tanks. Each of these platforms is 50% lighter than the average NATO tank. All weigh under 30 tonnes and have a good power-to-weight ratio. All are wheeled rather than tracked, offering operational mobility as well as performance at a tactical level. Like the StuG III or M18 Hellcat, they are highly flexible and able to switch between tank destroyer and assault gun roles. While the mechanical layout makes wheeled MGS platforms simpler than their tracked equivalents, turret sensors, optics and fire control systems are identical to those of a MBT, so few cost-savings are offered in this area. For sure, 8×8 mobile gun systems are less expensive to purchase and easier support than MBTs or tracked MGS platforms. Wheeled mobile gun systems typically cost from €8 to €10 million per vehicle instead of €12 to €14 million per MBT. This is still a worthwhile saving. 

Above: Japan’s Type 16 MCV has become an extremely successful contemporary assault gun. Similar in layout to Italy’s Centauro, it is an extremely efficient and inexpensive capability that is well suited to japan’s defence needs.

All things considered, the Stryker MGS, Centauro, and Type-16 are very much modern interpretations of the classic tracked assault gun. However, Italy and Japan’s adoption of these platforms is less about cost and more about the concept being aligned with their doctrine, which emphasises the need for wheeled systems that deploy rapidly by offering both operational and tactical mobility. Though less well protected than a MBT, the wheeled MGS has the capacity to travel long distances at speed. The downside of this is thinner armour. It means they must achieve a first-round kill. This underlines the need for high quality sensors and fire control systems. Despite obvious limitations, a less well-protected wheeled MGS will always be superior to the MBT that fails to turn-up in time to influence the outcome of a battle. To summarise these points, the relationship between modern mobile gun systems and main battle tanks is much more complementary than it was between WW2 tank destroyers and tanks. Contemporary mobile gun systems may now offer more utility and value than their predecessors. 

While the Centauro and Type-16 are undoubtedly successful designs, it should be noted that the US Army’s M1128 Stryker MGS is perceived to be less than ideal. It was fielded before it was fully developed and has proved unreliable in service. At inception, it was already close to the Stryker platform’s maximum weight limit, meaning that there was only limited scope to upgrade the platform further. The Stryker MGS has not been upgraded with the double-V hull that other Stryker vehicles now have. Despite its relative failure, the concept remains valid. It will be interesting to see what the US Army does either to upgrade or replace the Stryker MGS. One option could be to re-use the MPF turret (see below) on a Stryker with a low-profile hull. Or it could just buy Centauro 2. 

Above: GDLS Griffin III will be used as the basis for the US Army’s Mobile Protected Firepower requirement. This is intended to provide direct fire support for Infantry Brigade Combat Teams (IBCT). It mounts a 105 mm gun. Basic weight is 18 tonnes. Appliqué armour can increase protection from STANAG 4569 Level I to Level III with platform weight growing to 25 tonnes. (Image GDLS USA)

The modern day resurgence of the assault gun is also exemplified by the US Army’s Mobile Protected Firepower (MPF) programme. The goal is to provide Infantry Brigade Combat Teams (IBCT) with a vehicle capable of providing close fire support; in other words, a replacement for the M551 Sheridan. Presently Airborne and Light Role Infantry do not have organic fire support. The MPF platform will weigh between 18 and 25 tonnes, so it can be carried by C-130 or C-17 transport aircraft. Like its predecessor, it will also be air-droppable. Optional mission-configurable appliqué armour can be added to increase the protection level from NATO STANAG 4569 Level I to Level III. With a high power-to-weight ratio, MPF will be fast and manoeuvrable. It is expected to use banded rubber tracks, which will enhance mobility and ease of operation. The US Army plans to acquire 610 platforms. While some people view the MPF concept as a contemporary assault gun, others see it as Light or Medium tank. Whatever it is, it is a gun system that deploys in situations where MBTs like the M1A2 Abrams cannot get there quickly enough. 

Other armies are acquiring a similar capability by mounting 105 mm turrets on 8×8 infantry carrier vehicles. Patria has successfully mounted the John Cockerill Defence 30105 turret on its AMV Xp 8×8. Poland and Turkey are evaluating their own systems. One disadvantage of placing a heavy gun turret on a standard 8×8 APC hull is that it can potentially make the vehicle top heavy. Italy and Japan’s approach was to produce a specialist vehicle with a low-profile hull. This has the added benefit of reducing hull weight so that GVW is optimised. 

The People’s Liberation Army of China has recently acquired 600 ZTL-11 / ZBD-09 Snow Leopard 105 mm wheeled tank destroyers. This too utilises a low profile hull. The growing quantity of  wheeled MGS platforms in service shows that the concept has merit in contemporary warfare and is here to stay. 

Above: China PLA ZTL-11 Assault Gun with a 105 mm gun. This vehicle was introduced in 2013 and is amphibious despite weighing 23 tonnes.

So far, the UK has not revealed any plans to add an assault gun variant to its proposed Boxer line-up. Instead, Strike Brigades will be supported by Ajax-equipped reconnaissance regiments. As already noted, this will mount the CTAI 40 mm cannon firing cased-telescoped ammunition. Meanwhile, France plans to retire its AMX 10RC reconnaissance vehicle with a 105 mm gun, in favour of its 6×6 Jaguar EBRC reconnaissance vehicle, also with a CTAI 40 mm cannon. Additionally, Jaguar will be equipped with twin MMP anti-tank missile launchers. This poses the question of whether a cannon plus ATGM equipped vehicle is better than one with a 105/ 120 mm gun? The important point to make is that ATGMs can destroy enemy MBTs, whereas 105 mm guns may not. Does this men you need need to mount a 120 mm gun or not bother at all? Not necessarily. New ammunition natures for 105 mm guns can still inflict serious damage on MBTs even when they cannot pierce the front glacis plate. 

Standard UK Boxer Infantry Carrier Vehicles will all be equipped with a remote weapon station capable of firing Javelin ATGMs from under armour. It means that all section vehicles could potentially be tank destroyers. Add a box of light anti-structure missiles for taking-out bunkers and machine gun nests, and perhaps a mobile gun system is not needed at all?

As things stand, the British Army possesses just 227 Challenger 2s. This total is expected to be reduced to about 170 when it is upgraded to Mark 3 standard. Several retired senior officers have suggested that the UK needs somewhere between 250-300 MBTs. Others believe that the tempo of 21st Century manoeuvre warfare means that tanks will never be responsive enough to deliver timely effect. What is clear is that even with a reduced role, MBTs remain relevant, because no other combat vehicle can deliver the same level of firepower, resilience and shock effect. This being the case, one way to offset a reduction in tank numbers, is to produce a wheeled mobile gun system that is analogous to an MBT. 

Should UK Strike Brigades need to counter peer adversaries equipped with tanks, they may struggle with just a 40 mm cannon. If a 105 mm or 120 mm wheeled mobile gun system were added, we would have an extremely potent and flexible platform that offered increased utility across a wider range of deployment scenarios. There is also a more practical reason to prefer a gun solution to a missile solution – cost. Anti-tank missiles typically cost €70,000-€100,000 each, whereas the price of 105 mm and 120 mm APFSDS rounds is not more than €10,000-€12,000. The shorter time of flight of APFSDS rounds versus ATGM missiles may also be a factor when countering large numbers of enemy vehicles. Further, 120 mm HE rounds are likely to be much more effective against concrete emplacements than a burst of 30 or 40 mm HE rounds. If, as expected, strike brigades operate remotely at long distances, with several days between resupply, then carrying a larger amount of ammunition is essential. This also favours a 105 mm or 120 mm gun as 30-40 rounds of ammunition is much easier to stow than 15-20 anti-tank missiles. For all of the above reasons, a wheeled mobile gun system may be desirable. 

04. Envisioning a contemporary UK Assault Gun

With Boxer entering UK service, this is the obvious platform to use as the basis for a mobile gun system. Trying to balance utility with affordability, there are four potential Boxer MGS options:

  1. Mount a third-party gun turret on top of a standard Boxer mission module. 
  2. Mount a third-party gun turret on slightly modified Boxer driveline module with a reduced-height hull.
  3. Mount a third-party gun turret on a heavily modified Boxer driveline module with the engine mounted in the rear, allowing increased protection in front. 
  4. Mount a bespoke gun turret on heavily modified Boxer driveline module with the engine mounted in the rear, allowing increased protection in front. 

These options represent a sliding scale of cost versus sophistication and each will now be reviewed in turn:

Option A – Standard Boxer with MGS Mission Module

This option would be the simplest and least costliest MGS option to implement. The John Cockerill Defence 30105 turret could be easily integrated into a standard Boxer mission module. It would have a crew of three or four depending on whether an autoloader was used. There would be plenty of space in the rear of the vehicle for storage of additional ammunition and crew equipment. With a front-mounted engine, the crew could escape through the rear of the vehicle if it were hit. The turret weighs 6-8 tonnes, depending on the level of protection fitted. Since the crew sits almost below the turret ring, it would not need significant up-armouring. However, the weight of the turret on top of the mission module raises the vehicle’s centre of gravity, requiring uneven ground to be negotiated with care. Ammunition stowage, especially if extra rounds are stored in the crew compartment could impact survivability in the event of a penetration that causes an ammunition fire. Overall, however, the JCD turret is a simple and straightforward solution available at an attractive price. If a simple, no-frills MGS is required, then Option A is the default choice. 

Option A (Image: Ogden Dowcett)

This option makes the most of Boxer’s modular mission module approach, allowing units to configured according to mission. The options that follow require a modified hull to be developed. In comparing these concepts to the standard Boxer, it will need to decided whether advantages provided are worth the extra cost and reduction in overall platform flexibility.

Option B – Slightly modified Boxer with low-profile hull and COTS MGS turret

This option takes a standard Boxer driveline module and converts into a more focused weapons platform. The engine and gearbox would remain mounted in the same position, at the front of the vehicle, but the hull would be lowered and fitted with a permanent turret module capable of supporting a range of different turreted systems. While primarily envisaged as a mobile gun system, the low-profile hull could also mount a 155mm howitzer gun turret, a reconnaissance vehicle turret, an ATGM turret, an air defence turret, and an engineer demolition turret. All vehicle systems would be located in the same place, minimising the number of engineering changes to the platform and thus costs. Reducing the height of the vehicle reduces the silhouette, making the vehicle a smaller target. It also lowers the centre of gravity, improving stability, and compensating for the additional weight of the gun turret. The same John Cockerill Defence 30105 105 mm gun turret is proposed, because this is a reliable COTS/ MOTS solution that could be easily integrated. Though more sophisticated and thus more expensive than Option A, Option B would allow increased protection to be added to the vehicle without increasing GVW. 

This approached was used when the FV430 family of tracked vehicles was acquired in the 1960s. The standard high roof vehicle was the FV432 APC and this was used as the basis for the a Command vehicle (FV436), Repair & Recovery vehicle (FV434) and Anti-tank vehicle with Swingfire ATGM (FV438). It was also used for the FV433 Abbot self-propelled gun which mounted a 105 mm howitzer on a lowered hull. 

Option B (Image: Ogden Dowcett)

Italy’s Centauro MGS and Freccia IFV are also based on a common platform produced by OTO-Melara. Meanwhile, Japan has recently announced that its Type-16 MCV will spawn four further variants, including an APC/ IFV, Command, Reconnaissance, and Mortar carrier variants. These will take the basic low-profile hull and create a raised roof version.

Option C – Heavily modified Boxer (engine moved to rear) with low-profile hull and COTS MGS turret

This option re-engineers the Boxer driveline module to produce a dedicated specialist weapons carrier platform with minimal compromises. It re-locates the engine and gearbox to the rear of the vehicle, which allows the turret to be moved further forward, improving weight distribution and thus vehicle dynamics. It also allows extra protection to be added to the front of the vehicle without upsetting overall weight distribution and balance. In case this option seems unduly complicated, it is identical in concept to the British Army’s Saladin and Saracen 6×6 family. The Saracen APC had the engine mounted at the front. The Saladin CVR had the engine at the back. In reality, the two platforms were not radically different; the front and back of the vehicles were simply reversed around depending on the variant type. 

This approach, which dispenses with a separate mission module system, would still be modular in that it would allow a range of different weapon turrets to be dropped-in or swapped-out, depending on task. The challenge would be to ensure that the turret ring was large enough to accommodate the full range of turret types that might be employed. Where smaller turrets are used, a plug insert could be used to seal the turret ring. 

By reducing the height of the driveline and dispensing with a swappable mission module, the overall weight of the driveline would be reduced. This allows a heavier turret to be mounted plus extra armour to be added to the vehicle. In particular, it allows extra frontal armour to be fitted. 

Option C. (Image: Ogden Dowcett)

The Option C example shown features an OTO-Melara HitFact turret with a low recoil 120 mm smoothbore gun, which is the same weapon fitted to the Italian Army’s Centauro 2. Again, other off-the-shelf gun turret could also be used. 

Option D – Heavily modified Boxer (engine moved to rear) with low-profile hull and custom MGS turret

This option is identical to Option C, but goes one step further. This has a custom turret with a standard L/44 120 mm smoothbore gun. The larger turret allows a hydraulic recoil mitigation system to be fitted, reducing wear and tear on the driveline and suspension when the gun is fired on the move. In essence, Option D is a wheeled tank. 

This turret is based on the Leopard 2 turret, except that it has a larger ammunition compartment in the turret bustle, so that no rounds are stored in the hull. The ammunition compartment would have a blast-proof door and blow-off roof panels to isolate the crew from the ammunition in case the ammunition compartment was penetrated by enemy fire. It might also be possible to fit an autoloader that would further separate the crew from main gun ammunition. 

Option D is the gold standard variant. Even so, a significant customer user base would help to absorb non-recurring engineering (NRE) costs to ensure that unit cost was comparable to Option A. 

Option D. (Image: Ogden Dowcett)

In all cases, the maximum weight for a Boxer-based Mobile Gun System would be 36 tonnes (2.5 tonnes less than the Boxer RCH155 155 mm howitzer). A Boxer MGS might also employ a 800 kW engine to ensure cross-country agility. Given that Japan’s Type-16 MCV weighs 26 tonnes, a Boxer MGS would enjoy higher levels of protection, especially across the frontal arc.

For all of MGS options shown above, the most expensive aspect of each system would be their optics, sensors and fire control systems.

05. Conclusion

Ultimately, any decision to acquire the type of vehicle described above would be based on the need for such a capability and affordability. If a Boxer MGS costs 33% more than a standard Boxer, then the extra utility versus the price is likely to be worthwhile. But, if it costs marginally less than a regular MBT, then it will be much more difficult to justify. In other words, there has to be a compelling economic case to procure a Boxer MGS.

Above: From left to right: Boxer CRV with 30 mm Lance turret, Boxer ICV with 12.7 mm HMG, Option A, Option B, Option C, and Option D. (Image: Ogden Dowcett)

Any of the above vehicles, would provide utility in terms of direct fire support for Mechanised Infantry Battalions in an assault gun role. They could also perform reconnaissance tasks, acting as a screening force, as envisaged by UK Strike doctrine. They could also perform a heavy armour role in situations where Challenger 3 could not be deployed quickly enough. And, of course, a Boxer MGS could perform a defensive tank destroyer role. When Boxer IFVs are combined with Boxer MGSs, the resulting unit starts to blur the boundaries between a Strike Brigade and an Armoured Infantry Brigade. In a post-COVID-19 British Army, such flexibility could make all the difference, especially if it is more affordable than traditional tracked armour fleets. 

All things said, it must be emphasised that wheels do not replace tracks. There will be situations where the operational environment presents terrain that is inaccessible to wheeled vehicles. The Falkland Islands immediately spring to mind. Though it seems unlikely that we would need to deploy a task force to evict an invading army again, should the need arise, a vehicle like the BVS10 Viking would still be essential. 

If cost does becoming al limiting factor, there are still other ways to deliver an assault gun effect at a reduced cost. Kongsberg, MOOG, Elbit and Rafael have all showcased modular remote weapon stations. Capable of mounting a mix of different weapons depending on the task at hand they are a neat way of making limited budgets stretch further. A potential mix of weapons could include two or three of the following weapon types: 

  • Light cannons (e.g. 30×113 mm M230LF)
  • Grenade launchers (e.g. 40×53 mm GMG HV)
  • Heavy machine guns (e.g. 12.7×99 mm HMG)
  • ATGM (e.g. FGM-148 Javelin) 
  • LASM (e.g. MBDA’s Enforcer) 
  • Air Defence missiles (e.g. Starstreak HVM)

In the final analysis, UK Boxer vehicles will be equipped with Kongsberg Protector RCWS with a 12.7x 99 mm HMG plus a Javelin ATGM. This may be sufficient to counter asymmetric threats, but not a peer adversary. Even though the Ajax 40 mm CT cannon is a formidable weapon that will do an admirable job supporting mechanised infantry units, we will at some point need a Boxer with more firepower.

Above: MOOG modular weapon station family. (Image: MOOG)