Semi-Auto Shotgun Pistol: MAUL = AWESOME

The Metal Storm MAUL has finally be unveiled and it is awesome. Previously only computer rendered images of the weapon were publicly available. The light 2.75 lbs 12 gauge shotgun has no moving parts and comes in a pistol and a rifle under-barrel configuration. Five rounds can be loaded at a time into the barrel and each is fired electronically.

Picture 4-36

The official video:

Last year I blogged that the US Navy was funding the MAUL development. The MAUL should not be confused with the Metal Storm multiple grenade launcher, the 3GL, which uses similar technology.

[ Why do all the interesting things happen when I am officially not blogging 😉 ]

Hat Tip: Defense Update

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • Valhalla

    Amazing… now you can have your point man carry his M4/M16A4 and this, instead of having to work around an extra Mossberg 590 or SPAS-12.

    How long you think before deployment in military settings?

    SWAT must also want this, 12 Gauge less lethal or something. Get 12 gauge gas grenades, instead of full size one shot under barrel grenade launchers.

  • Fred

    Wonder what kind of loads it’s firing, there’s pretty much no recoil.

  • Ryan

    I just watched a future weapons episode with their machine guns and pistols in it. I just kept asking how do you reload? Apparently that was kind of a glaring error or the show creators were retards because they never went over that other than to say replacing the barrels. Changing barrels would be horrible – that’s the part in the gun that absolutely needs the most precision manufacturing to be accurate. Looks like they may have some other methods for relading too though.

  • Random Joe

    virtually no recoil, no ear protection, what visually appears to be about 200-300 fps and sounds just like a gas paintball or airsoft gun steadily running out of charge as the magazines are run out.

    definitely cool, but, hrmm…

  • Dom

    @Fred: I agree! It says it’s a 12-gauge, but it looked like he was shooting .22 shotshells in the pistol grip configuration. Also, I’m pretty sure we could see the projectiles starting to drop in the first shot. I guess they were sandbags. I’d like to see buckshot.

  • If there was ever a whiz-bang awesome piece of technology I sincerley hope comes to fruition, this would pretty much be it…

    As for the reloads, the orginal versions of the technology required barrel swap-out, but the ammunition is contained entirely within the barrel – there is no receiver or magazine or anything like that. They seem to have moved on to a tube-in-the-magazine methodology from the video, but it will definitely warrant further research.

  • iMick

    I’ve seen them reload the 3GL and its exactly the same as an M203, but you insert 3 stand alone grenades, one after the other up the barrel from the breach. I am assuming the loading principle would be the same for the MAUL.

  • Juan

    No recoil? 12 gauge? 2 lbs?

    Come on… I thought that physics’ laws were still respected 😀 😀 😀

    • Juan, obeyed? Yes. Respected? No 😉

      I think the rounds were low powered less-lethal ammo.

  • Valhalla

    I just had an idea of the use for SWAT.

    M4/other small Assault Rifle
    Less Lethal Grenade launcher (tear gas, and what not)
    This as a less lethal side arm with 12 gauge rubber slugs or something, low powered to stun.

    But I would like a demonstration with full powered 12 gauge buckshot.

  • Simon_the_Brit

    I’m sure this is a solution to a problem that does not exist 😉

  • What Simon says. There is NO shortage of ideas to project less-than-lethal force, and NO shortage of equipment to do it.

    There IS a shortage of new ideas for CQB (lethal) equipment.

    MetalStorm started out as an idea to project an overwhelming amount of lethal force. It had important applications for area-denial tactics.

    This business of using it in a low-powered version to project LTL loads is NOT what we need in a new weapons system, but it might reflect the direction we are going to go in with our new wuss Commander-in-chief.

    What I would like to see MetalStorm develop is a serial-loaded 12-ga system with rounds having a low-powered launch charge, but a high-velocity rocket motor, getting them to the target at least trans-sonic at 25 meters or less. During the ‘Nam war, a company, GyroJet, pioneered something like that, but aside from making locator flares for downed airmen, they never sold the idea to the DOD. The handheld locator flares had a max velocity of 1100 fps, IIRC, and WERE used to defeat enemy soldiers on a couple of occasions.

  • Matt Groom

    I saw this at the NDIA show in Las Vegas this week. 1.8Lbs of 12 gauge goodness.

    DO WANT!

    This is a very good use of this technology. There are not currently any rapid firing, compact, lightweight, less lethal weapons on the market, so even if this concept only worked for less lethal applications, it would still be a good idea.

    The only thing they had at the show other than Less Lethal rubber tipped rounds was Steel Slugs. I was assured by the Metal Storm people that this was DEFINITELY being developed for use of Buckshot. I get the distinct impression that these models were in the proof of concept stage, but the concept works, and it’s probably the most innovative thing I saw at the show.

    The magazine tube/barrel holds five rounds, and is inserted from the front. Empty tubes are ejected and a new tube inserted in their place. The tube is not reloadable in the field, since it must be reloaded in a clean room, but they are theoretically reusable. It is un-rifled, since it’s intended to work as a shotgun. I asked if the slugs would be gyroscopically stabilized, Ala Gyrojet, and they said no.

    I personally believe this technology should be installed on every M4, and with the adoption of modern rifle grenade designs, would make every serviceman more lethal, more versatile, and less encumbered vs. carrying an M203 or say a conventional shotgun and a pistol.

  • J.A. James

    Those happy days of failure to breach a door on the first round could be things of the past. I just can’t but get warm, fuzzy feelings at the thought of a pair of these brutes mounted side by side. If two five round bursts of 12ga breaching rounds won’t unlock the door, you really need to be using high explosives.

    Now here’s a thoroughly bothersome question. What parts of a fielded MetalStorm system are the US BATF-E going to classify as the ‘Firearm’? The barrels? They have the ignition system and part of the fire control. The receiver? Depending on configuration, it can be as simple as battery storage and the Safe/Fire switching systems.

    Having never lost my amazement at the ingenuity found in young, bored, badly supervised soldiers, I can say from personal experience that a TOW Missile round can be fired with nothing more than some wires and a big enough battery. Same for a Dragon and the old Redeye.

    Will there come a time when a stack of five 12ga shells is considered a DD by the US Fed? I haven’t seen any of the current prototypes from MetalStorm but I did get to see one of their 40mm testbed guns at Picatinny a number of years ago. Pretty much anybody who’s able to read the pinout schematic of a computer IDE connector could read the schematic for the connectors in the 40mm grenade launcher. That puts it back in the realm of some wire and a big battery.

    As always, YMMV. Seems today is a bit of a Get-Snarky-With-Stupid-Bureaucracies day for me…

    • J.A., good point. There has been some talk about a handgun firing “normal” handgun rounds using the metal storm principal. The barrel would probably have to be the upper reciever.

      Out of interest, how did you come to know that an expensive missile could be fired with a battery? 😉

  • J.A. James

    In the early 80s I was assigned to the 1/509 (ABCT) based in Vicenza, Italy. Combat Support Company had two TOW platoons, the Redeye platoon as well as my own Recon/Scout platoon.
    During one of our seemingly endless number of training deployments, we were in northern Turkey taking part in a joint NATO exercise. Several members of the Recon section as well as a few TOW bunnies and some other folks from the Bn were sent to a brief training session conducted by the 10th Special Forces Group out of Bad Tolz, West Germany. We had some guys from the 2nd Para in the UK as well as some Turkish Paracommandos, a few of the Italian Paracaduti Alpini troops and some guys from Belgium and the West German Falschirmjager Regiment. We had missiles, we had a lot of free time, it was northern Turkey in August so I still blame the heat for anything that might have been considered to be “poor judgement.”

    Nobody was terribly impressed with anybody elses normal jobs so discussions turned to ‘What If’ scenarios. One of the scenarios was, “What if your TOW jeep is put out of commission and takes your tracker and other electronics with it?” Schematics were viewed, dust covers were removed from the missile, wires were connected, many people suddenly found a really strong desire to be a long way away and behind the biggest rocks they could find.

    It was a hell of a show when it fired. To this day I think an early generation TOW missile would make a pretty outstanding off-route anti-armor mine. A lot more effective than any of the other systems then in the inventory. I’m not quite sure how you’d aim the damned thing but if that could be worked out, it would make a pretty spectacular impression on a wayward enemy armored vehicle.

    The Redeye guys refused to be outthought by a bunch of grunts so as I understand it, later in the day one of their training rounds was successfully set off. As for the Dragon, one of the methods to destroy it was listed in the operator’s manual as, “fire the missile either conventionally or by field expedient means making sure to elevate the muzzle high enough that even without the electronic control of the tracker-sight it will travel far enough to arm and subsequently detonate down range.” (words pretty much to that effect) Though given the number of outright stupidity in the Army’s field manuals of the time, I probably shouldn’t take it as gospel since the only place I saw the reference was in the manual. The Dragon was a lot of fun to watch being fired though, it hopped around like a malevolent beagle as it made its way toward the target. Sounded like a string of firecrackers going off.

    • Daniel, thanks for the update.

  • i would much rather have an an AA-12 fully automatic shotgun with barely any recoil at all

  • Anthony Cresto

    Very cool tech, practical for LTL. However I think there will be some significant problems, aside from the reloading setup.

    The shells are stacked end to end right? So the first discharge will have a different performance compared to the last discharge. With less barrel length, it will probably have a wider pattern and will have less force behind the shot or slug. But with the last shot, the pattern will probably be tighter and more powerful. I don’t pretend to know the math, just the theory, but I wouldn’t put my life in the hands of a weapon with that much variance.

  • GhostSteel

    Actually performance is reported to have been tested to be very consistent. The reload essentially is a “barrel change” in that the disposable carbon fibre tube which serves as the “magazine” also serves as the barrel. The MAUL weighs under two lbs and the 4oz ammunition tubes can be rapidly released and reloaded. It’s truly radical projectile technology.

    From wiki:


    The concept of superposed load or 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. Adam O’Fallon’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[2].

    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 “munition tubes” which can be transported more readily than individual shells, and inserted directly into Metal Storm barrels. Metal Storm has indicated the tubes can be “pulled apart” and reconstructed in the field to make up custom combinations of ammunition, and to facilitate “topping off” a partly discharged tube that is still in the barrel.”