Innovation and Adaptation
Indirect Machine Gunnery for the Motorised BattalionBy Chris Thorburn August 19, 2019
Imagine having the ability to direct suppressive fire on to a target from distance without ever revealing the location of your machine guns to the enemy.
In the Australian Army this capability is a reality. In the infantry, Direct Fire Support Weapons (DFSW) soldiers are charged with providing the suppressive fire necessary for manoeuvre elements to close with and kill the enemy.
At present, extended range machine gunnery (ERMG) is a specialist skill that takes weeks to teach to a trained infantryman, and as yet the Army has not worked out how to achieve ERMG from a mounted firing platform.
My idea seeks to address this capability gap.
How? By transforming a machine gun mounted in a protected weapon station (PWS) into an ERMG.
This would enhance Army’s ability to manoeuvre in two ways. First, it would turn any vehicle equipped with a PWS into a mobile indirect fire support platform. Second, it would increase the survivability of motorised combat teams and battle groups by allowing PWS machine guns fitted to Bushmasters and Hawkei Protected Mobility Vehicles to be employed from defilade.
Best of all, by using existing technology this capability would require very little investment to establish and could be easily integrated into the current PWS course.
In short, the capability would provide an interim fire support solution to the motorised battalions until future technologies such as loitering munitions are acquired.
Principles of indirect machine gunnery
To understand how indirect machine gun fire could be achieved from a vehicle platform, it is best to start with an explanation of how DFSW soldiers establish fire positions.
A dismounted DFSW section in an ERMG role is composed of two machine guns mounted on tripods. Each gun is equipped with four spare barrels, and a C2 sight and post.
Put crudely, the purpose of an ERMG drill is to turn a machine gun into a compass. This is done by levelling and paralleling the section or platoon’s guns, fixing each gun to a known reference point (the post), and adjusting the scales of the C2 sight. Adjusting the scales of the sight ensures that bearings taken from the gun’s location on a map align with the actual direction of the gun’s barrel on the ground. Once the scales have been adjusted, the gun will align with a target once a bearing has been inputted into the sight, and the gun has been brought on to post.
This part of the drill ensures that the gun is pointing the right way.
The purpose of the second aspect of the drill is to get the gun firing at the correct range. To do so, a DFSW section or platoon commander measures the distance between himself and the target and the difference in elevation between his guns and the target. Because the guns are firing from a fixed and stable firing position (a tripod) the trajectory of the rounds is fixed. Because the trajectory of the round is fixed, the section commander is able to use a predicted data table to calculate the elevation required to achieve rounds on to target.
Skilled and well-practised gun crews can set up a gun in this manner in six minutes and switch targets in less than thirty seconds. These are impressive skills, but skills that could easily be automated by a fire control system (FCS).
Proposed system: automated indirect Protected Weapon Stations (PWS)
Three pieces of equipment are required in order to achieve accurate indirect fires from a mounted platform.
First, a stabilised weapons platform that is able to level and adjust the bearing and elevation of a gun automatically and stable enough to guarantee the shape and size of a beaten zone.
Second, a FCS that is able to mimic the drills of a human DFSW crew.
Third, a heavier barrel to sustain the rate of fire required, or at least a barrel rack that allows the operator to rotate hot barrels within the vehicle.
To use such a system, a soldier would simply need to input a target grid and his or her location, load and fire the weapon, and change barrels and fix stoppages as required.
As the principles of machine gunnery are weapon agnostic, any weapon that is capable of forming a beaten zone could be mounted to the system provided that the ballistic character of that particular weapon was inputted into the system. Such a system would transform the PWS from a direct fire weapon system into an indirect platform capable of achieving fires out to a significant distance with the .50 calibre heavy machine gun (HMG), and the MK47 automatic grenade launcher (AGL).
I am not proposing that such a system would replace DFSW Platoons within motorised battalions or that such a system would turn the Bushmaster or Hawkei into a fighting vehicle.
Vehicles will never be able to achieve surprise in the same way that dismounted DFSW soldiers can.
Moreover, due to basic geometry the closer a dismounted element is able to get to a target, the longer they are able to suppress an enemy position. Therefore, only dismounted call signs are able to provide the amount and quality of suppression necessary for a deliberate dismounted attack that achieves break-in and successfully exploits an enemy’s position.
Most manoeuvre commanders would also accept that the best way to conduct motorised operations is for dismounted call signs to clear the ground whilst their vehicles remain to the rear. However, in situations where speed is of the essence troops may be forced to remain mounted in their vehicles.
In such instances, whether withdrawing or in the pursuit, the ability for vehicles to remain behind cover whilst troops dismount, and then manoeuvre in support of their own troops, is a desirable capability. This is particularly the case where a motorised combat team or battle group is unsupported by armoured call signs who would ordinarily be able to guard the main body’s flanks.
An indirect weapons platform would not negate the inherent limitations of the Bushmaster in these sorts of operations but it would go some way in mitigating its vulnerabilities.
Once contact was made with the enemy off the line of march, motorised commanders could push their vehicles up to flanking fire support positions.
Provided the Bushmaster or Hawkei crew had crest clearance to the target, the dismounted manoeuvre commander could then call for fires from his mounted call signs.
Fires would then be able to be adjusted on to the target, controlled and cut-off by any soldier qualified as a Mobile Fire Controller, Gun Fire Controller, or Joint Fire Controller.
At present, indirect machine gunnery is a skill maintained by a small minority of the infantry in DFSW Platoons. In theory, there is no reason why these skills could not be mimicked by a relatively simple robotic weapon platform. This platform could be mounted to any Bushmaster and Hawkei in the Australian Army.
For relatively little investment, Army could provide motorised commanders with the ability to call upon an organic fire support platform whilst conducting dismounted clearances. This would provide motorised infantry commanders with greater tactical flexibility when not being supported by armoured, mortar, DFSW, or artillery callsigns, significantly improving their ability to fix and manoeuvre against the enemy.
Indirect machine gunnery guards against the Bushmaster and Hawkei’s inherent vulnerability against direct fire and anti-armour weapons and, if employed cunningly and intelligently, enhances the lethality of motorised combat teams and battle groups on the battlefield.