A folding gun is a unique weapon that offers concealment, while also ensuring the operator is ready for action. Unfortunately, the designs are typically expensive, and oftentimes the demand isn’t enough to warrant mass production. The guns are like something out of the past and future, and they’re capable of collapsing into shapes that look nothing like the dangerous weapons they really are.
Hotchkiss Type Universal
Following the Second World War, the French military realized a new compact submachine gun was necessary to arm troops partaking in rigorous physical and close-combat operations. In 1949, three years after the call for a new design, the Société des Armes à Feu Portatives Hotchkiss et Cie submitted what it called the “Type Universal” – or Type 010.
The submachine gun chambered thirty-two 9 x 19 mm rounds fed from an MP 40-pattern magazine. It fired from a closed bolt, with a cyclic rate of approximately 650 rounds per minute. When not in use, the stock could be folded under the barrel, and the magazine well and magazine rotated to fit between the U-shaped buttstock.
Hotchkiss described the folding gun as “the individual defense weapon meeting the requirements of the most modern Armies and Police. Folded up, it is very compact, easy to transport, conceal and parachute. It is quick to set up and comes unfolded in the form of a carabiner.” With a retractable telescopic barrel, the weapon could collapse to a length of just 17.25 inches.
Drawbacks included a narrow, uncomfortable buttstock and sight, as well as an uncomfortable pistol grip. Ultimately, the Hotchkiss Type Universal was deemed too complex and expensive for mass production, and the submission was rejected. However, it’s believed around 7,000 were produced, with most exported to Venezuela and Morocco.
The ARES FMG (“Folding Machine Gun”) was designed by Francis J. Warin while he was working for ARES Inc. The increase in kidnappings of high-class businessmen in South America during the 1980s inspired him to develop the weapon, with the aim of arming civilians who were at risk of becoming the victims of crime.
The submachine gun’s compact design allowed it to be easily concealed, while also unfolding to full size in a matter of seconds. It’s believed only five were constructed and tested, and it later went on to influence similar weapons developed in Ukraine and Russia.
The ARES FMG’s design offered a compact size of only 10.3 inches when folded, and it was capable of firing 650 rounds per minute. It operated through a blowback firing action, and chambered 9 x 19 mm cartridges. A 32-round magazine could be equipped, but this prevented the folding action. So a 20-round magazine was preferred.
The folding action divided the weapon into three components: the receiver, the hollow shoulder stock, and the grip and trigger. It collapsed into a box shape, which allowed the stock to fold over the pistol grip, concealing it under the receiver.
The Russian Konstruktorskoe Buro Priborostroeniya (KBP) Instrument Design Bureau created its own folding submachine gun, which shares a resemblance to the ARES FMG. Similarly designed for close-quarters combat, it was intended for use by Special Operations teams with the Ministry of the Interior of the Russian Federation (MVD).
Unlike other folding guns, the PP-90 chambers the 9 x 18 mm Makarov cartridge. When collapsed, the pistol grip and magazine are folded under the barrel and covered by the stock; it folds into a rectangular box without protrusions, making its concealment all the more easier. Folding down to around 11 inches, it can be easily carried in a holster, bag or shoulder rig.
The barrel’s muzzle can be fitted with a suppressor, and, unlike other folding guns that omit sights for the sake of compactness, the PP-90 uses a flip-up iron sight capable of folding down into the receiver.
The PP-90 also uses a manual safety/fire selector switch. On the side of the receiver, a safety toggle provides two settings: “P” (safe) and “O” (automatic). By selecting the safety setting, the weapon mechanically disables the bolt catch. It’s also designed to prevent accidental discharges, making it impossible for the gun to fire when in a folded position. On top of this, it’s incapable of firing until the stock is fully extended.
The internal safety mechanism is also equipped with a drop safety, which prevents the PP-90 from discharging when dropped.
Magpul Industries designed a folding submachine gun prototype in 2008 known as the FMG-9. Just like similar weapons, it was hinged, so the pistol grip was tucked between the receiver and the stock when stowed.
The model never left the prototype stage, halting as a proof of concept. However, in 2010, Magpul released the Folding Pocket Gun (FPG), which was almost identical to the FMG-9. The difference was that the FPG’s firing mechanism was that of an Airsoft KWA G18C replica. The FPG fires 6 mm pellets from a 49-round magazine, and has a range of 45 meters.
In 2021, Magpul and ZEV Technologies introduced two new versions of the FMG-9: the Folding Defensive Pistol (FDP-9) and Folding Defensive Carbine (FDC-9). The FDP-9 is available for purchase in the form of a complete, large-format pistol. Owners can purchase a conversion kit to legally turned the weapon into the FDC-9, reclassifying it as a short-barreled rifle.
Around the same time the ARES FMG was being produced, Utah Connor was developing his own version of a folding gun. Called the UC-9 (Under Cover – 9 mm), it caught the attention of Tim Bixler of the South Central Research Company, who contacted his friend, David Boatman. The three soon went into business together.
Renamed the DEB M21 (David E. Boatman Model 21), the submachine gun was intended for use in undercover police work. It collapsed, and was equipped with a carrying handle that not only helped make it less noticeable, but also served as a set of sights for the operator.
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In 1986, the Hughes Amendment became the Firearms Owners Protection Act (FOPA), which made the production of machine guns more difficult. The company manufacturing the DEB M21 subsequently went bankrupt, with only one UC-9 and nine DEB M21s ever produced.
That being said, the DEB M21 did get its 15 minutes of fame after making an appearance in the 1990 film, RoboCop 2.