Beyond the Boxer 50 Cal

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Is the 12.7mm/.50cal Heavy Machine Gun (that will arm UK Boxers) enough firepower for a vehicle that will form the vehicular backbone of the British Army?

The M2 ‘Fifty Cal’ is an enduring design that has seen off numerous attempts to replace it. Older than B-52, or even (whisper it) the FV432. Infrequently used in a dismounted role, the majority of users now have them in Remote Weapon Stations, and the UK is no different.

Boxer 50cal Background

Our RWS of choice is the Kongsberg Protector RS4, manufactured under licence by Thales in Glasgow.

The most recent £180m order was for 500 of them, together with the same number of Acusonic shot detection systems, the same as used on Ajax.

The RS4 is the latest iteration and is now fully GVA compliant, has multi-axis stabilisation, offers the ability to be remotely controlled from outside of the vehicle and can be operated by multiple crew stations, a very clever piece of equipment that allows the maximum range of the mounted weapon to be fully exploited. It adds 135kg of top weight, plus the weight of the weapon and ammunition. It will feature a Thales Catherine-EZ cooled thermal imager, Thales CELT3 laser rangefinder and Kongsberg VIS95 daylight camera.

Depending on one’s point of view, at over 50kg plus 20kg’s worth of ammunition, it is either too heavy or reassuringly solid. Many also remark that it lacks power for such a large vehicle, and one that might encounter 14.5mm or 23mm armed adversaries.

The 2019 Army Combat Power Demonstration (ACPD) took place on Salisbury Plain from 28 – 30 Oct 2019. It was set in and around Copehill Down Village - the Army’s primary urban combat training facility - and showcased a variety of the Army’s most modern capabilities.<br data-lazy-src=

Of course, many of these conversations tend to coalesce on individual weapons rather than concepts of employment for the Mechanised Infantry Vehicle (MIV), but it is also fair to say that the enemy also gets a vote and we might not always have the luxury of employing them as we wish. Ukraine has also provided a stark reminder that low-cost UAS can be devastatingly effective, even when armed with improvised weapons like freefall mortar bombs with 3D printed tail fins.

Thus, the target set is not just a technical with a 23mm, it is a DJI drone with a mortar bomb.

If we did want to start a conversation about dipping into the optional extras list, where would we start?

Upgrade to a 20mm Automatic Cannon

The mechanical simplicity of the M2 has much to commend it, recoil-operated and absolutely rock-solid. The faster firing M3 might be a quick-to-adopt option (they are already in service on Army Air Corps and Fleet Air Arm Wildcats) but it is difficult to see any advantages, the higher rate of fire perfectly suits a helicopter, but not a vehicle.

Going to something like a 20mm automatic cannon might offer some advantages and a relatively easy upgrade path but it is not all plain sailing.

There are quite a few 20mm automatic cannons still in production. The AE 20mm or Alexis 20mm weigh about the same as an M2 but have significantly more powerful ammunition. The Alexis weighs 49kg and has an effective range of 1,500m, with a selective rate of fire of 300 or 750 rounds per minute, with TP Target practice, TP-T Target practice Tracer, AP Armour piercing, AP-T Armour piercing Tracer, HEI High explosive incendiary and an MP Multi-purpose round.

The Nexter M621 is another example of a simple, recoil-operated, 20mm automatic cannon, as is the Rheinmetall KAE. The Nexter M621 has recently been selected by the German Army for special forces use in a manually aimed ring mount.

The new Sky Viper from General Dynamics is also another interesting option.

20x113mm, 20x128mm and 20x139mm ammunition is manufactured all over the world, in widespread use with plenty of natures available.

Recoil forces would likely be higher, and the number of rounds carried, decreased.

A couple of questions spring to mind with the various 20mm automatic cannon options.

Can the Thales/Kongsberg RS4 handle the increased recoil forces and is the juice with the squeeze?

On the former, not sure, although it is fair to say that the basic weights of an M2 and most of these 20mm options are quite similar, and recoil compensation is quite a complex subject, which is a roundabout way of saying don’t know. But assuming it can, the most pressing question is an advantage versus cost and a reduced number of rounds carried. Effective range and terminal effects are certainly improved, but for the most likely target sets and requirements, are they that much of an improvement, again, one for discussion?

Their lack of effect against small drones would also have to be considered.

Just as an aside,

AEI has done a lot of work on recoil energy attenuation and some have claimed that the Venom 30mm LR can be a direct drop-in replacement for 12.7mm M2, shown below on a Valhalla Midgard RWS

Maybe with a look to see if it can be operated from an RS4?

Perhaps one thing to look at is the extended height turret that German Boxers deployed to Afghanistan with, designed to provide improved depression angles.

Fitting Javelin

This is actually a pretty easy upgrade.

As far back as 2016, the Armoured Trials and Development Unit (ATDU) conducted a number of trials with a Kongsberg Protector (RS4) mounted on a CVR(T) Spartan (image above). Five missiles were fired during the trials, three Block 0 missiles at 1,500m, 2,500m and 3,200m, and two Block 1 missile at 3,500m and 4,300m.

All were successful.

The Thales promotional material states the RS4 is ‘Javelin Enabled’.

Javelin is already in service.

Not every module needs a Javelin but it would be a very quick and cheap option.

Air Bursting 40mm HV Grenades

Although you see them less than the 12.7mm Heavy Machine Gun in promotional materials, the Thales RS4 can absolutely also mount the 40mm Grenade Machine Gun. With an ability to fire High Velocity 40mm grenades, it could provide overlapping and complementary options to the 12.7mm HMG, to a similar range.

The GMG does not have a dual feed capability so any change in nature would require manual intervention so dual purpose natures seem to be the most common, available from many sources. So far, air-bursting 40mm HV grenades do not seem to have entered widely into service but options are certainly there. To enable this, a change to the weapon is needed, Nammo is marketing a product called the MPU that allows existing 40mm AGLs to be quickly modified for their air-bursting natures.

Upgrading the software to exploit the possibilities of air-bursting 40mm high-velocity grenades is also another factor to consider, although Nammo used an H&K 40mm GMG and an RS4 for their trials, so it doesn’t on face value seem an impossibility.

Nammo 40mm HEDP-RF is shown below.

Exploiting the newer air-bursting grenades, there are also some interesting counter-UAS solutions becoming available, the Aselsan Atom and a similar product from Nammo/Escribano.

With an effective range of about 500m, these counter-UAS grenades have obvious limits, but then again, they use an existing weapon that is widely deployed and in service, something is better than the square root of nothing. Part of a layered approach to the counter UAS problem, with offboard detection, seems worth looking at.

Upgrade the RWS and Go Large

If we want to go to 25mm or 30mm, again, lots of options and these open up the potential for air-bursting natures for effective counter UAS capability.

But this would mean upgrading the RWS.

The RS4 goes back some way and is part of a family of RWS that includes the much larger RT60.

Upgrading to the RS6 or something like the Moog RIwP might provide additional options, 20-30mm automatic cannons, for example, take your pick, there are quite a few options, e.g. Nexter M781, General Dynamics M230LF or AEI Venom LR

Any of these large RWS would significantly change the nature of Boxer., and that might be a conversation worth having, but not today.

A Few Thoughts

What have we learned from switching horses mid-course, what have we learned from changing requirements whilst still in the manufacturing stage?

The absolute very last thing we want to do is start modifying existing contracts, so any discussion must start with the RS4, at least for the bulk of Boxer vehicles (talking about more heavily armed support or recce variants is an entirely different conversation)

This means in practice, two weapons for any improvements, the 40mm Grenade Machine Gun, and Javelin ATGW.

We have both in service.

Personally, I think it makes sense to look at Javelin and air-bursting natures for the 40mm GMG, and mix those with the 12.7mm HMG, these are all proven weapons with integration either already done or simple enough on the RS4. Air bursting 40mm also opens the door to a wider counter UAS capability.

Then, and only then, start to look at the sweets in the 30mm shop.

Stay on course, get Boxer into service as planned, and maybe make a few tweaks to what we have planned, but no more. (we might already have these in the pipeline anyway)

And to close, a picture of the RS4 with 12.7mm HMG, on a Boxer, with Javelin.

See you in the comments.

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