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An underwater firearm is a firearm designed for use underwater. Underwater firearms or needleguns usually fire flechettes or spear-like bolts instead of standard bullets. These may be fired by pressurised gas.[ citation needed ]
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Underwater firearms were first developed in the 1960s during the Cold War as a way to arm combat divers.
Because standard bullet ammunition does not work well underwater, underwater firearms commonly fire flechettes instead of standard bullets.
The barrels of underwater pistols are typically not rifled. Rather, the fired projectile maintains its ballistic trajectory underwater by hydrodynamic effects. The lack of rifling renders these weapons relatively inaccurate when fired out of water. Underwater rifles are more powerful than underwater pistols and more accurate out of water, but underwater pistols can be manipulated more easily underwater.
Among the many engineering challenges in designing underwater firearms is that of developing a weapon which can be effective both underwater and out of water. The ASM-DT amphibious rifle is an early example of such a weapon. First fielded by the Russian special forces in 2000, the folding-stock ASM-DT amphibious rifle is capable of firing two kinds of ammunition, both of 5.45 mm caliber:
When used against underwater targets, an underwater firearm may have a longer range and more penetrating power than spearguns. This is useful in such situations as shooting an underwater intruder where the projectile may have to first penetrate a reinforced dry suit, or a protective helmet (whether air-holding or not), or a thick tough part of their breathing set and its harness, or the plastic casing or transparent cover of a small underwater vehicle.
Supercavitating ammunition that functions better underwater has been developed by Defence & Security Group (DSG), a Norwegian company. The Multi-Environment Ammunition (MEA) series supercavitating rifle ammunition, developed and marketed by DSG, is anticipated to be useful for certain special operations, including underwater warfare. These include defensive applications such as diver protection, and offensive applications such as neutralizing enemy divers, VBSS (visit, board, search, and seizure) operations, MIO (maritime interception operations), GOPLATS (Gas and oil platform) boarding operations, speedboat interdiction and neutralization, anti-submarine warfare, anti-torpedo operations, and certain counter-piracy operations. [2]
The ballistic characteristics of MEA series ammunition allows the user to fire at an underwater target from above the water, an above-the-water target from underwater, or an underwater target from underwater. This ammunition allows the user to fire from above the surface into the water at a very low angle of incidence—in some cases as low as two degrees—without ricochet. After entering the water, the bullet will continue its original trajectory. The user, when aiming the gun, needs to compensate for the refractive index of the water (roughly 1.333 for fresh water at 20 °C (68 °F)). [2]
MEA series supercavitating ammunition is currently available in the following calibers: [2]
The underwater capabilities of MEA series supercavitating ammunition allow it to be used for unmanned underwater vehicle (UUV) applications. The armed UUVs can be used in both offensive and defensive underwater warfare operations. Using the .50 BMG supercavitating cartridge, an armed UUV can potentially destroy steel-hulled underwater objects from a distance of 60 m (200 ft), or could potentially hit a target 1,000 m (3,300 ft) in the air from a location 5 m (16 ft) below the surface. [2]
A firearm is any type of gun that uses an explosive charge and is designed to be readily carried and used by an individual. The term is legally defined further in different countries.
A rifle is a long-barreled firearm designed for accurate shooting and higher stopping power, with a barrel that has a helical or spiralling pattern of grooves (rifling) cut into the bore wall. In keeping with their focus on accuracy, rifles are typically designed to be held with both hands and braced firmly against the shooter's shoulder via a buttstock for stability during shooting. Rifles have been used in warfare, law enforcement, hunting and target shooting sports.
A bullet is a kinetic projectile, a component of firearm ammunition that is shot from a gun barrel. They are made of a variety of materials, such as copper, lead, steel, polymer, rubber and even wax; and are made in various shapes and constructions, including specialized functions such as hunting, target shooting, training, and combat. Bullets are often tapered, making them more aerodynamic. Bullet size is expressed by weight and diameter in both imperial and metric measurement systems. Bullets do not normally contain explosives but strike or damage the intended target by transferring kinetic energy upon impact and penetration.
A cartridge, also known as a round, is a type of pre-assembled firearm ammunition packaging a projectile, a propellant substance and an ignition device (primer) within a metallic, paper, or plastic case that is precisely made to fit within the barrel chamber of a breechloading gun, for convenient transportation and handling during shooting. Although in popular usage the term "bullet" is often used to refer to a complete cartridge, the correct usage only refers to the projectile.
Supercavitation is the use of a cavitation bubble to reduce skin friction drag on a submerged object and enable high speeds. Applications include torpedoes and propellers, but in theory, the technique could be extended to an entire underwater vessel.
A needlegun, also known as a needler, flechette gun or fletcher, is a firearm that fires small, sometimes fin-stabilized, metal darts or flechettes. Theoretically, the advantages of a needlegun over conventional projectile firearms are in its compact size, high rate of fire, and extreme muzzle velocity. The needle presents less frontal area than a bullet, producing less drag and thus more effective range than a wider projectile of the same mass and velocity. There have been experiments to make guided flechettes that can home in on targets.
The .22 Long Rifle, also known as the .22LR or 5.6×15mmR, is a long-established variety of .22 caliber rimfire ammunition originating from the United States. It is used in a wide range of firearms including rifles, pistols, revolvers, and submachine guns.
The Special Purpose Individual Weapon (SPIW) was a long-running United States Army program to develop, in part, a flechette-firing "rifle", though other concepts were also involved. The concepts continued to be tested under the Future Rifle Program and again in the 1980s under the Advanced Combat Rifle program, but neither program resulted in a system useful enough to warrant replacing the M16.
The Gyrojet is a family of unique firearms developed in the 1960s named for the method of gyroscopically stabilizing its projectiles. Rather than inert bullets, Gyrojets fire small rockets called Microjets which have little recoil and do not require a heavy barrel or chamber to resist the pressure of the combustion gases. Velocity on leaving the tube was very low, but increased to around 1,250 feet per second (380 m/s) at 30 feet (9.1 m). The result is a very lightweight and transportable weapon.
The APS underwater assault rifle is an underwater firearm designed by the Soviet Union in the early 1970s. It was adopted in 1975. Made by the Tula Arms Plant in Russia, it is exported by Rosoboronexport.
The SPP-1 underwater pistol was made in the Soviet Union for use by Soviet frogmen as an underwater firearm. It was developed in the late 1960s and accepted for use in 1975. Under water, ordinary-shaped bullets are inaccurate and very short-range. As a result, this pistol fires a round-based 4.5 millimetres (0.18 in) caliber steel dart about 115 millimetres (4.5 in) long, weighing 12.8 grams (0.45 oz), which has longer range and more penetrating power than speargun spears. The complete cartridge is 145 millimetres (5.7 in) long and weighs 17.5 grams (0.62 oz).
The Heckler & Koch P11 is an underwater firearm developed in 1976 by Heckler & Koch. It is loaded using a pepper-box-like assembly, containing five sealed barrels each containing an electrically-fired projectile. Two styles of barrel assembly can be used: one containing five 7.62×36mm flechette darts for use underwater, or five 133-grain bullets for use above water.
The Advanced Combat Rifle (ACR) was a United States Army program, started in 1986, to find a replacement for the M16 assault rifle. Under the stress of battle the average soldier with an M16 may shoot a target at 45 meters, but hit probability is reduced to one out of ten shots on target by 220 meters. Because of this, the ACR program was initiated in the late 1980s to create a weapon that could double the hit probability. The ACR program was preceded by older programs such as the Special Purpose Individual Weapon. The program ended in 1990 after an expenditure of approximately US$300 million.
The Heckler & Koch HK CAWS is a prototype automatic shotgun—designed as a combat shotgun—co-produced by Heckler & Koch and Winchester/Olin during the 1980s. It was Heckler & Koch's entry into the U.S military's Close Assault Weapon System program.
A powerhead is a specialized firearm used underwater that is fired when in direct contact with the target. Powerheads are often used for spear fishing and against sharks or alligators for sport, defense, or to kill nuisance animals. The term powerhead refers to the firearm-like part of the device; when attached to a shaft to form a spear, it may be referred to as a bang stick or shark stick. The spear in question may be handheld or launchable from a spear gun.
The ASM-DT is a Russian prototype folding-stock underwater firearm. It emerged in the 1990s.
The following are terms related to firearms and ammunition topics.
The ADS is a Russian assault rifle specially made for combat divers. It is of a bullpup layout and is chambered in the 5.45×39mm M74 round. The ADS can adapt a suppressor and optical sights.
The .300 AAC Blackout, also known as 7.62×35 mm, is an intermediate cartridge developed in the United States by Advanced Armament Corporation (AAC) for use in the M4 carbine. The cartridge yields increased performance in shorter barrels and effective subsonic performance for silencer use when compared to 5.56 mm NATO. The .300 AAC Blackout uses standard 5.56 mm NATO magazines and components with the exception of the barrel.
The FN 5.7×28mm is a small-caliber, high-velocity, smokeless-powder, rebated, non-tapered, bottleneck, centerfire cartridge designed for pistols and personal defense weapons (PDW) uses, manufactured by FN Herstal. It is similar in length to the .22 WMR and .22 Hornet. Unlike many new cartridges, it has no parent case; the complete package was developed from scratch by FN.
