HAMMR and the changing job of the infantry grenadier

HAMMR does not look like artillery. In the footage, a soldier carries it through woodland as part of his normal fighting load. He moves with the rest of the section, drops into position and shoulders the weapon much as he would a rifle. Then a small drone appears above the trees and the same weapon is brought onto an aerial target.

That short sequence tells us far more about where infantry weapons are heading than a list of specifications.

For decades, the infantry grenadier has occupied a fairly well understood place within the squad. Give a soldier an under-barrel launcher or a standalone 40 mm weapon and he gains the ability to put explosive effects beyond the reach of a hand grenade. It is useful against troops in the open, firing positions, windows and other point targets. Push much beyond that and the squad starts looking elsewhere for heavier fire support.

HAMMR starts to blur those divisions.

American Rheinmetall’s Highly-Advanced Multi-Mission Rifle is based on the company’s SSW40. It is a magazine-fed, semi-automatic 40 mm shoulder-fired weapon weighing about 4 kg empty and measuring roughly 80 cm long. It uses Rheinmetall’s 40 x 46 mm medium-velocity ammunition, giving the system an engagement range of up to 900 metres. The weapon can also fire existing 40 mm low-velocity ammunition.

That alone gives a squad considerably more reach than a conventional 40 mm launcher.

The ammunition is where things get more interesting.

Rheinmetall offers programmable airburst rounds designed to detonate around targets protected by cover. Its ammunition family includes high-explosive fragmentation, multi-mission and dual-purpose rounds intended for use against light and medium armour. The company has also paired the US version with an Aimpoint FCS15 fire-control system and C-UAS tracking software.

HAMMR is not currently a standard US Army weapon. American Rheinmetall developed it around the Army’s PGS requirements, and it should be viewed as a proposed capability rather than something already heading to every American infantry squad.

The Army requirement itself, however, is significant.

The US Army asked industry for a soldier-portable, semi-automatic, magazine-fed system capable of engaging personnel in the open and behind cover. It envisaged the weapon becoming the soldier’s primary weapon rather than an occasional specialist tool. More revealingly, the Army said the capability should reduce squad dependence on artillery, mortars, aviation and other fire-support organisations.

That changes the grenadier’s job.

From grenade launcher to fire-control system

With a traditional grenade launcher, much of the skill sits in understanding range, trajectory, ammunition effects and the limitations of the weapon.

HAMMR adds another layer.

The soldier is now carrying a weapon, a family of ammunition and a digital fire-control system. One target might be infantry exposed in the open. The next could be behind a wall. Another might be a vehicle. Seconds later, the target could be a small drone moving across the sky.

The weapon can help calculate the shot. It cannot remove the judgement involved in deciding what should be engaged, which effect is appropriate and what sits around or behind the target.

This means the grenadier starts to resemble a small fire-control operator.

Consider a target behind cover. The soldier has to identify what he is looking at, understand the geometry of the position, determine the appropriate ammunition and use the sight and weapon as a combined system. The objective may no longer be putting a grenade through an opening. An airburst round creates the option of producing an effect around that position.

Now change the target.

A small drone appears above the squad.

The visual problem is completely different. The target is smaller, moving in three dimensions and may only remain exposed for seconds. The grenadier has moved from engaging a ground target at a known location to acquiring and tracking something moving through the air.

Then change the situation again.

A vehicle appears beyond the tree line.

The operator now has to think about the target, ammunition and desired effect again.

One soldier. One weapon. Three very different engagements.

That is a much bigger training problem than learning how to shoot a grenade launcher.

The return of an old idea, with a much broader mission

There is an obvious historical comparison with the XM25 programme.

The attraction of the XM25 was never simply that it fired a grenade. Its selling point was giving an individual soldier the ability to attack an enemy protected by cover using a ranged and programmable airburst munition.

HAMMR approaches the same operational problem from a different direction and adds capabilities that have become far more pressing since the XM25 era.

The most obvious is the drone.

Small UAS have moved from an occasional battlefield curiosity to a routine feature of modern fighting. Infantry units now need ways of detecting, avoiding, disrupting and destroying them. Many existing counter-drone systems sit above the squad level or depend on electronic warfare, specialist weapons or supporting units.

Putting a credible C-UAS option into a weapon already carried within the squad changes that equation.

It also creates an interesting shift in the relationship between individual weapons and supporting fires. The Army’s own PGS requirement explicitly talks about reducing dependence on other units for fire support.

Nobody is replacing a mortar platoon with a 40 mm rifle.

But the boundary is moving.

A squad able to produce airburst effects against protected infantry, engage targets approaching a kilometre away and respond to a small drone possesses options that would have been difficult to place in the hands of one soldier a generation ago.

The weapon is getting smarter. Training has to follow.

This is where the discussion moves away from HAMMR itself.

New weapons tend to attract attention through range, weight, ammunition and lethality. Those numbers are easy to compare.

The harder question is what happens to the soldier carrying one.

An operator might need to move between conventional direct engagement, targets behind cover, vehicles and aerial threats during the same tactical problem. Fire control reduces some of the calculation required to make those engagements. It does not remove the need to recognise the situation and make the right decision.

You cannot solve that training requirement simply by putting more rounds down a range.

Live firing remains necessary. Rheinmetall itself produces ballistically matched training ammunition for its 40 mm family, allowing soldiers to train with rounds that reproduce the flight characteristics of operational ammunition.

But ammunition alone cannot cheaply reproduce the range of situations the soldier now needs to experience.

You need targets appearing at different distances. Troops behind cover. Moving vehicles. Drones approaching from different directions. Friendly forces moving through the same area. Changing terrain. Poor visibility. Multiple threats appearing almost together.

Then the instructor needs to change the problem and run it again.

And again.

This is where synthetic training earns its place alongside the live range.

With BattleVR, we are increasingly interested in this part of the training problem. The system provides tracked weapons, adaptable tactical environments, AI-controlled actors and detailed after-action review inside an immersive environment.

For a weapon such as HAMMR, the interesting application is not creating a virtual firing range.

It is reproducing the whole engagement.

A squad moves through terrain. A threat appears behind cover. The grenadier identifies it and reacts. A drone enters the area. The tactical situation changes. A vehicle arrives. Other members of the squad are moving and engaging at the same time.

The instructor can then replay what happened.

Where was the grenadier looking when the drone appeared? How long did he take to react? What target did he prioritise? Where were his own troops? What ammunition did the situation call for? Did he remain fixed on one threat and miss another?

Those are far richer training questions than asking if the round hit the target.

BattleVR was designed around repeatable tactical training and detailed AAR rather than a single pass through an exercise. That becomes more significant as individual weapons acquire fire-control systems, programmable ammunition and new target sets.

The live range teaches the soldier what the weapon does.

Synthetic training can give him far more opportunities to learn when to use it.

A different kind of grenadier

HAMMR is interesting because it represents something larger than another infantry weapon competing for space on the soldier.

The technology being pushed down towards squad level is becoming much more capable. Fire control is improving. Ammunition is becoming programmable. Small drones have created an entirely new class of immediate threat. Tasks that once sat across several weapons and levels of command are moving closer to the individual soldier.

That soldier now has more decisions to make, and less time to make them.

A future grenadier may still need all the traditional skills associated with firing a 40 mm weapon. He will also need to understand digital fire control, different munition effects, protected targets, moving aerial threats and the consequences of using those capabilities around friendly forces and civilians.

HAMMR can put a remarkable amount of firepower into one soldier’s hands.

The harder task is making sure his training keeps up with it.