Metal Storm' ballistics technology
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Metal Storm Limited (ASX : MST) is a research and development company that specializes in electronically initiated superposed load weapons technology. Metal Storm is both the name of the company and the technology.

The company is based in Brisbane, Australia with a subsidiary in Arlington, Virginia, U.S.A. Metal Storm owns the proprietary rights to the electronic ballistics technology invented by J. Mike O'Dwyer. The company has over 30 worldwide patents covering aspects of ballistics technology.


How it Works.

Metal Storm stacks its projectiles in the barrels nose to tail.  Metal Storm technology achieves its unique performance by having the ability to fire each round independent of the other.  In other words when the propellant of one round in the stack is ignited the other rounds are not affected.  

Rather than using a firing pin impacting on a primer, Metal Storm weapons are electronically fired.  A computerised fire control system precisely controls the firing signal to each round in the barrel.  As there is no need to mechanically reload the barrel after each round is fired, Metal Storm has complete control over the timing and rate of fire.   As a result, the weapon can be used to deliver a single round or dozens of rounds instantaneously at the target. Moreover, when combined with airburst munitions, Metal Storm weapons can use precisely timed firing to create a pattern of fragmentation and blast to meet specific needs, such as to intercept an incoming RPG or missile.

Due to the light weight of Metal Storm barrels, most non-infantry configurations use multiple barrels, usually between 4 and 64.  This provides increased firepower and the ability to mix munitions - to have a weapon configured to respond to different threats in different ways - such as having less than lethal or marker rounds instantly available as an alternative to the use of lethal force.

Today, Metal Storm converts conventional munition warheads, such as 40mm grenades, into Metal Storm munitions by attaching a special Metal Storm tailpiece, containing the propellant and primer.  With this approach, Metal Storm can quickly adapt the certified warheads preferred by its customers to be used in a Metal Storm weapon system. 


What is Metal Storm Technology.

Metal storm technology is an electronically initiated, stacked projectile system that removes the mechanical elements required to fire conventional weapons.  Effectively, the only moving parts in Metal Storm technology are the projectiles themselves.  Multiple projectiles are stacked in each barrel.  The technology allows each projectile to be fired sequentially from each barrel. 


The concept of stacked projectiles (multiple projectiles loaded nose to tail in a single gun barrel with propellant packed between them) predates Metal Storm. The roman candle, a traditional firework design, employs the same basic concept; however, the propellant for the leading projectile continues to burn in the roman candle's barrel, igniting the charge behind the subsequent projectile. The process is repeated by each charge in turn, ensuring that all projectiles in the barrel are discharged sequentially (and inevitably) from the single ignition. Various methods of separately firing each propellant package behind stacked projectiles have been proposed which would allow a 'single shot' capability more suitable to firearms.[1]

J. Mike O'Dwyer, an Australian inventor, observed that these methods did not eliminate the problem of unintended propellant ignition caused by hot gases 'leaking' back up the barrel. Mike O'Dwyer's original Metal Storm patents demonstrated a method whereby projectiles placed in series along the length of a barrel could be fired sequentially and selectively without the danger associated with unintended propellant ignition.

In the original Metal Storm patents the propellant immediately behind the projectile closest to the muzzle of the gun barrel was ignited by an electronically fired primer, the projectile was set in motion, and at the same time a reactive force acted on the remaining stacked projectiles in the barrel, pushing them backwards. By design, the remaining projectiles would distort under this load, expanding radially and sealing against the gun barrel wall. This created a seal which prevented the hot propellant gases (expanding behind the lead projectile) prematurely igniting the remaining propellant charges in the barrel (blow-back). As each of these propellant charges was selectively (electronically) ignited, the force 'unlocked' the projectile in front and propelled it down the gun barrel, and reinforced the radial expansion (and hence the seal) between the projectiles remaining in the barrel and the barrel wall.

Subsequent designs discarded the 'distorting shell sealing against the barrel' concept in favor of containing the propellant in 'skirts' that form the rear part of each projectile. These skirted projectiles differ from conventional 'shells and cartridge' units in that the skirts are part of the projectile, and in that the skirts are 'open-ended' (at the rear). The rearward seal to the skirt is provided by the nose of the following projectile in the barrel. As in the previous design, the firing of a projectile results in a rearward impulse on the remaining projectiles stacked in the barrel. This results in the skirts of the remaining shells in the barrel being compressed against the following shell heads, effectively creating a seal that prevents hot gases in the barrel triggering unintended propellant ignition ('blow-back') along the length of the barrel. Metal Storm also introduced inductive electronic ignition of the propellant, effectively from outside the barrel. This overcame technical issues in maintaining physical contacts with the propellant charges, which due to the compression effectively 'shift' slightly backwards within the barrel during firing.

The skirt-to-nose joint has in recent designs incorporated an easy-release arrangement which allow the shells to be clipped together to form robust ammunition 'tubes' which can be transported more readily than individual shells, and inserted directly into Metal Storm barrels. Metal Storm have indicated the tubes can be 'pulled apart' and reconstructed in the field to make up custom combinations of ammunition, and to facilitate 'topping up' a partly discharged tube that is still in the barrel.



The distinguishing features of this technology are the absence of ammunition feed and casing ejection systems (the only moving parts are the projectiles), and the electronic ignition of the propellant charges. The relatively simple external shape of the Metal Storm barrel allows for the clustering of Metal Storm barrels into a barrel array or 'pod', or for their attachment (as single units) 'bolted on' to existing weapons mounts, including infantry weapons. The absence of a mechanical feed mechanism and the inherently compact lightweight nature of Metal Storm systems also makes them suitable for attachment to light robotic ground and aerial vehicles. The electronic ignition allows for the firing of the stacked ammunitions at 'electronic speed' without any delays caused by mechanical ammunition feed mechanisms. The electronic firing also creates the potential for tighter integration with electronic targeting systems, with electronically programmable fuses in air burst ammunition, and with (in the case of hand guns) electronic grip recognition technology.

The clustered barrel array has been further developed with the design and building of prototypes of electronic firing control systems, allowing selective firing from any barrel in a cluster, and within each barrel the ability to control the rate of fire. This allows for responses which range from the equivalent of a volley gun discharge (all projectiles 'at once') to using (selectively) individual munitions with increasingly serious (but non-lethal) effects and lethal munitions including high explosive and air burst shells (all from different barrels in the array). The ability to deploy a range of munitions from effectively 'one' weapon system, and to selectively escalate responses from the non-lethal to lethal without reloading, has been put forward by the company as an advantage in urban warfare and insurgency situations where a range of responses may be quickly required in close quarter fighting and crowd control.

A patent exists for a design where the gun tubes at the edges of the array are angled outwards from the main axis so that a gun tube array mounted on a tracking platform would have the potential to engage a target before the bulk of the centrally located gun tubes reached the optimal aiming position. This feature, combined with the 'always loaded' nature of the technology, and the potential to rapidly produce a very high density (low distance of separation) of projectiles 'in the air' is put forward by the company as an advantage for this technology in close-in weapons support roles.

Manual, automatic and semi-automatic reloading concepts exist, incorporating breech and muzzle loading into permanent barrels, replaceable barrels (and barrel arrays), a belt-fed stacked-cartridge gun patent, and a patented breechless continuous feed gun with injected propellant. With the exception of the belt-fed and the breechless gun patents, all of Metal Storm's gun concepts are limited to bursts of no more than the number of projectiles pre-loaded into the barrel(s). That said, a barrel array might contain more projectiles in fact than a traditional 'clip' or 'belt'. Latest projectile designs (2007) incorporate a head to tail clip-together feature, allowing the rapid construction and deconstruction (in the field) of ammunition 'tubes' from individual shells. These tubes can be inserted directly (and locked) into Metal Storm barrels.





The Redback weapon system is being developed under a teaming agreement with Electro-Optic Systems (EOS), Metal Storm (MS) and Singapore Technologies Kinetics (ST Kinetics). The Redback is a 4-barrel, 16-shot remotely operated weapon system that can automatically track targets and slew at speeds of up to 700 degrees/second (almost 2 complete revolutions per second). The primary role of Redback is as a lightweight vehicle or fixed asset mounted 40mm weapon system. The Redback can utilize high explosive, enhanced blast, and air bursting munitions, all of which have been successfully test fired, as well as a suite of less-than-lethal munitions such as gas, smoke, sponge, CS (Capsaicin) and illumination. An enhancement to undertake autonomous engagement and intercept of multiple Rocket propelled Grenades (RPGs) is being developed and tested.



Firestorm is a light-weight, remotely-operated weapon system developed under a SBIR contract with the US Army in 2007. The 4-gun, 40mm robotic weapon system is a versatile platform capable of firing a family of both lethal and less-than-lethal munitions including high explosive, airburst, flash-bang, payload (selectable CS, tear gas, and inert smoke payloads), frangible nose (selectable marking, inert or CS powders), and blunt impact foam rounds. As such, Firestorm provides a flexible solution to various situations and applications including area denial, fixed asset, crowd-control, vehicle protection and many other robotic applications. The Firestorm system consists of a robotic mount with controllable azimuth and elevation capability, a modular, drop-in gun pod, consisting of four electronically-fired, stacked-round, 40-mm launchers mounted in a recoil-mitigation cage, and a sighting and targeting package. The system is currently configured for plug-and-play operation, requiring DC power and an ethernet connection. System operation is simplified with an intuitive fire control user interface installed on any computer. Though still a prototype, the system has been tested and verified and continues to be optimized in anticipation of future production.



Core to the Firestorm weapon pod is the GLL4042 40mm, electronically-fired, stacked-round launcher. With no moving parts, the weapon is invulnerable to mechanical failures such as jammed bolts, and broken firing pins. The launcher can achieve extreme rates of fire, surpassing those obtainable using traditional firearms. The cyclic rate of fire enables trailing rounds to be fired before leading rounds leave the barrel, resulting in projectiles spaced less than a foot apart in flight. The GLL4042 is capable of launching both lethal and less-than-lethal munitions, and offers round-detection capability for munition balance feedback to the user. The GLL4042 is not configured to be fired as a stand-alone weapon and requires direct connection using a military cable to the fire control unit. Linear magazines are pre-loaded with stacked munitions and breech-loaded into the launcher before fired. Several demonstrations of the product have already been performed to audiences including the army, navy and civilians.



The 3GL weapon system is being developed under a teaming agreement between Metal Storm (MS) and Singapore Technologies Kinetics (ST Kinetics). The 3GL is a 3-shot under-barrel grenade launcher intended to replace the M203 under barrel grenade launcher. The 3GL can also be detached from the 'host' rifle and operated as a stand-alone weapon. The 3GL is intended to be able to be mounted to the bulk of military rifles currently in use (while maintaining existing mounting points such as a picatinny rail) including the M16, AK-47, SAR 21, T.A.R. 21 and Steyr AUG. Load, unload and top-up of projectiles can be done individually via a sliding breech mechanism. On February 4, 2009, defence technology specialist Metal Storm Ltd has also achieved a major milestone by successfully certifying its semi-automatic 3GL grenade launcher for safe man-firing. Following extensive testing and successful certification, several 3 round semi-automatic volleys were man-fired at an outdoor range in Queensland. It was the first stacked-round shoulder firing of a certified grenade launcher from the Brisbane-based weapons developer. Metal Storm aims to commence production of the 3GL in 2010. Military evaluation company Nova Defence has independently reviewed the 3GL and reported that with appropriate planning and support Metal Storm's objectives for the weapon were "entirely achievable."



The Multi-shot Accessory Under-barrel Launcher (MAUL) is an electronically-fired,12-gauge shotgun for use as an accessory weapon to the M4 rifle. Immediately succeeding bench testing and verification of the concept launcher under a contract with the Marine Corp War Fighting Laboratory, follow-on funding to develop the prototype accessory weapon was awarded by the Office of Naval Research (ONR) in mid 2008. An emphasis on minimal weight, lean profile, and functional simplicity will dictate the design and fabrication of the completed weapon system. With a 5-shot, lethal and less-than-lethal (LTL) capability, the MAUL will offer versatility in special missions, military police, SWAT, and all-purpose defense applications.


36 Barrel Prototype

Metal Storm has created a 36-barreled stacked projectile machine gun, boasting the highest rate of fire in the world. This weapons system has a firing rate capability of slightly more than one million rounds per minute. However, the recoil is so great that it cannot be practically mounted on any kind of vehicle, and no device has yet been proposed to reload the gun automatically.[2]


Widespread public awareness of Metal Storm technology was due to media coverage in relation to the theoretical 1 million rounds/minute rate of fire. In the United Kingdom it was featured along with its inventor on the popular BBC show Tomorrow's World. As a result of this, and other publicity, there have at times been unrealistic expectations of the technology, particularly in regard to the ease with which such technology might be developed and implemented.

Some limitations with the technology became apparent during the late 1990s as development continued. Much of the detail of the technology remains classified but it is understood that:

  • While the simplified mechanics and relative light weight of Metal Storm gun/barrel array suggested that they might have advantages when deployed on light unmanned aerial vehicles, it was anticipated that recoil management may become a significant issue relative to the light weight of the vehicle and consequently to flight stability. However, a Dragonfly Pictures DP-5X unmanned helicopter (in free flight) has since been demonstrated firing Metal Storm 40mm weapons.
  • High barrel pressures were noted in early testing when multiple shells were 'fired' so rapidly that the second (and subsequent) shells were in motion within the barrel before the first had left the muzzle of the gun. While this resulted in very high muzzle velocities (the origin of the Mach 5 technology that was investigated by DARPA[citation needed]) it also (appeared) to cause concern about barrel wear and barrel integrity. Metal Storm took out a patent on a barrel pressure relief valve system; but has concentrated in recent years on the development of low pressure 40mm systems, and has in recent demonstrations deployed a microchip at the barrel muzzle which detects the passage of each projectile and locks the firing mechanism (of each subsequent shell) until the first shell has cleared the muzzle. This still allows for much higher rates of fire than conventional weapons, but appears to guard against unintended high pressure situations in the barrels.