Caliber: 40mm (others possible)
Type: stacked-projectile, caseless multishot system
Overall length: n/a
Weight: n/a
Effective range: up to 400 m
Capacity: 3 shots (current 40mm model, single barrel)
The Metal Storm grenade launching system is a radical step from
most conventional firearms. Using the ancient principle of an
"Roman candle", Metal Storm weapon systems currently are promoted
in a variety of calibers and applications. One of such applications
is the 40mm, multi-shot grenade launcher, that could be either
mounted on the infantry rifle to create an enchanced-capability
infantry weapon like the Australian AICW system, or to be mounted
on stationary or vehicle platforms in multi-barrel
configurations.
Key advantage of Metal Storm system is its mechanic simplicity. In
fact, the standard Metal Storm grenade launching unit is no more
than a single rifled barrel, loaded with several projectiles,
stacked one upon the another. There are no loading mechanisms, no
feed units nor magazines or belts - each barrel is a magazine
itself. Projectiles are fired using powder charges, located in the
hollow hase of each projectile, and there's no case left to extract
and eject after each shot; Powder is ignited by the electric
ignition system, wired to the electrinic fire control module
through small ports in the wall of the barrel. When user press the
firing button or trigger, electronic fire control module sends the
ignition impulse to the charge of the foremost projectile in the
stack; when trigger is pressed for the second time, module ignites
the second charge and then next, until barrel is empty. Once all
the rounds in the barrel are shoot out, it can be removed from the
host and then either collected and later sent to factory for
reloading, or simply discarded.
Current 40mm grenade launching module, developed for the AICW
rifle/GL system, contains three grenades stacked one in front of
another in single barrel. Each barrel has an electronic interface
which is connected to the fire control unit, built into the host
platform. This is about the simplest systems, at least from the
operator's point of view (from developer's point of view, there's
plenty of complications and difficulties, most of which seems to be
already overcome). However, there is one drawback when Metal Storm
system is compared to existing mechanically or manually reloaded
systems - latter systems still can be fired once batteries are dry;
Metal Storm always require some sort of electric power to operate.
This problem may seem critical, especially for military purposes,
but, actually, it is not. For example, several Soviet/Russian
anti-tank grenade launchers (like RPG-16 or RPG-29) are built using
electric rocket ingnition; necessary electricity is provided by the
magneto-impulse generators, powered by the pull of the trigger.
Same idea also could be possibly applied to the Metal Storm
system.
http://world.guns.ru/grenade/gl18-e.htm
If i am not wrong Singapore have tied up with the Australians on
Metal Storm technology. So i am wondering if we have developed a
similar multi-shot grenade launcher for our SAR-21 much like what
they have done to their Steyr-AUG. I think it is possible as both
the SAR-21 and the Steyr are of bull-pup designs. Check out the
link for a diagram. 
