International warfare has created some of the most profound advances in technology and concepts, and the underwater arena is no exception. Following up on last issue’s look at the pistols of combat divers in Russia’s, Germany’s and America’s navies, we dive here into long guns of frogmen.
The APS or Avtomat Podvodnyj Spetsialnyj Underwater Rifle was developed during the early 1970s by the Soviet Central Institute for Precision Machine Building (TsNIITochMash plant). The inspiration for this was that Russian combat divers only had knives and the SPP-1 underwater pistol (see American Shooting Journal, June 2015 issue) as their sole means of weaponry. The APS was meant to provide considerably more firepower to their combat divers.
The APS, initially only used by the Russian armed forces, has been available on the international market since the fall of the Soviet Union. It’s based on the AK-74, a refined version of the AK-47 chambered in 5.45×39mm rather than the more commonly known 7.62×39mm of other earlier Kalashnikov rifles, but with several significant changes. It fires a 120mm-long, 5.6mm dart, or flechette, which is relatively stable travelling underwater. The weapon has a smoothbore barrel, and relies on the shape of the flechette for stability and accuracy. The flechette is fired using a standard 5.45×39mm cartridge that has been waterproofed. The polymer magazine holds 26 rounds, and is unusually deep from front to back because the long projectiles dictate its shape.
Like the AK, the APS uses a gas piston to operate; however, this system features a self-adjusting gas valve that allows the weapon to be fired efficiently at varying depths as well as on the surface. Unlike the AK-74 it fires from an open bolt, which ensures that the barrel remains filled with water to properly stabilize the projectiles.
The APS rifle performs differently at different depths because of the increase in water pressure. At greater depths the cyclic rate of the weapon slows down and the muzzle velocity and effective range decreases. At a depth of 16.4 feet, the APS is considered to have an effective range of 98.4 feet, which decreases to 36 feet at a depth of 131 feet.
The APS rifle solved the problem of arming Russian divers while they were stationed at a naval base, but the problem still remained on how to arm them when they were deployed on surface missions where the APS was of little or no use. These combat divers ideally required a weapon capable of providing them with the same level of reliability on the surface or underwater.
The divers were faced with the unsatisfactory solution of having to carry separate weapons for each possibility. What they needed was a single hybrid weapon.
In 1991 the Artillery Engineering Institute in Tula, Russia, solved the problem by creating the ASM-DT rifle. This rifle was designed to fire two different types of projectiles. Underwater it fired the same flechette dart as the APS, and when on the surface it fired the standard 5.45x39mm round. The weapon was able to accept both the APS and an AK-74 magazine.
To achieve this duality, the weapon was fitted with a long magazine port and a sliding magazine catch. When the catch was positioned towards the rear of the magazine port, the rifle could accept the APS underwater magazine. When the magazine catch was moved to the middle of the magazine port, the rifle could accept an AK-74 magazine. In this position the rear unused portion of the port was covered with a spring-loaded dust cover. When the magazine release was shifted to the forward position the gas system automatically adjusted for firing underwater.
One of the ingenious alterations was a shallow-groove rifled barrel. This allowed the 5.45x39mm round to be more accurate above water, and also purposely allowed the gases to push ahead of the round in order to blow any remaining water out of the barrel. This prevented the barrel from bursting if the rifle was quickly transitioned from under to above the water without having to drain
Additional accessories included various types of optical and night sights, as well as tactical lights. The rifle has a folding stock, which along with the pistol grip and handguard are made from impact-resistant plastic. This weapon could also be equipped with a GP-25 grenade launcher, a bayonet or a sound and flash suppressor.
The ASM-DT was not a perfect solution because the diver still had to carry two different types of ammunition and magazines; however, its performance underwater was equal to the APS, and on the surface it performed almost as well as the AK-74. This weapon came into limited service with Naval Spetnaz teams in the Russian Federation Navy in 1980.
The main problem with ASM-DT was that it had to use extremely long, specially designed underwater ammunition when submerged. The rifle needed an overly long receiver, a complicated adjustable magazine well and two types of magazines. The first thing that had to be done was the complete redesign of the ammunition.
The design bureau in Tula went back to the drawing board. This time they developed a more effective underwater round that retained the compact size of the standard issue 5.45×39mm round, and it could be loaded and fired from a standard AK-74-type magazine. This round would also have the ability to be fired through the same chambers and barrels that would accept the above-water ammunition. They called it the 5.45mm PSP round and it was designed with a specific shape that produced a cavitation bubble, which stabilized the round underwater for greater accuracy.
There are two types of PSP ammunition, the 5.45 PSP (combat ammunition) with a hardened-steel projectile weighing 16 grams and an air muzzle velocity around 330 meters per second, and the 5.45 PSP-U (practice and training ammunition) with a bronze projectile weighing 8 grams, and an air muzzle velocity of about 430 m/s. The effective range with PSP ammunition varies from 82 feet at a 16-foot depth to 59 feet at a 65-foot depth. The effective range of the PSP-U training ammunition when below water is about half of the combat round.
When designing the ADS Dual-Medium rifle, the engineers at Tula moved away from the basic AK-74 rifle platform, which had been the base concept for the APS and ASM-DT underwater rifles. The new design was derived from the A-91M Bullpup rifle which had previously been designed at Tula earlier in 1990s. The new weapon retained the bullpup layout, gas-operated action with a rotary bolt action. The gas system was modified with the addition of a manual air/water environment selector. Some parts of the A-91M had to be redesigned and materials were revised to work reliably when submerged in saltwater.
An integral 40mm grenade launcher that fires a VOG-25 caseless grenade can be fitted to this rifle and is fired by using a secondary trigger located inside the trigger guard. The grenade launcher barrel is detachable and can be removed if not required.
The muzzle of the barrel is threaded to accept a muzzle brake or a sound suppressor and is fitted with adjustable iron sights. An integral carrying handle is provided with a Picatinny-type rail on the top to accept various day and night optics. The ADS can fire any standard issue 5.45x39mm ammunition above water with the same accuracy and effectiveness as that from an AK-74 general-issue rifle. When submerged and loaded with 5.45mm PSP ammunition the ADS outperforms both the APS and ASM-DT underwater rifles for accuracy. The ADS came into service with the Russian Navy special forces in 2013.
The Soviet Union was the first to begin developing firearms specifically for their combat divers. The Soviet Navy was worried about divers attacking their ships in their naval anchorages, and in particular those of the Black Sea fleet based in Sevastopol, located on the Crimean Peninsula, and Odessa, Ukraine. These anchorages could be easily threatened by NATO forces operating out of Turkey. It wasn’t an idle worry. The use of divers to attack anchored ships was used extensively by the Italian Navy during World War II, and the British Navy developed their techniques by using captured Italian equipment.
The Soviet Navy had as many as 1,000 combat divers in their Black Sea fleet,
but averaged about 300 in most other naval bases. Known as Naval Spetnaz
divers, these divers were not trained to the same level as US Navy SEALs, but then again, they had a more limited role in protecting their fleet from underwater attacks than US teams.
The designer of the first underwater pistol was Dmitry Shiryaev of the TsNIITochMash plant, otherwise known as the Central Research Institute for precision machine building, a Russian industrial-design bureau. In the early 1960s, he designed the B-VI-307, a simple four-barrelled hinged-break pistol that fired a flechette, or tiny arrow, rocket-assisted 7.62mm round. These rounds stabilized in water by using a cavitation bubble. This bubble was generated around the front of the flechette by the specially designed shape of the nose. When fired above water, however, the round was for all intents and purposes useless. The flechette tumbled once it left the barrel and was only capable of causing a wound at point-blank range.
To accommodate the thick neoprene gloves worn by divers operating in subfreezing waters, the trigger guard and combination safety lever and barrel-hinged lock were oversized. Although this weapon was produced in small numbers and tested by the Soviet Navy, it was not adopted, reportedly because the rocket-assisted round was too advanced for the military at that time.
The design team went back to the drawing board and created the SPP-1 pistol. This was basically a cruder version of the B-VI-307 and cheaper to produce. This gun retained the simple break-open design with a cluster of four smooth-bore barrels and double-action trigger, but the rocket-assisted projectile was abandoned in favor of a simple 4.5mm rimmed cartridge flechette-firing round utilizing a conventional cartridge propellant. The round was protected against water by using a sealant in the neck and a lacquer coating on the primer. The flechette also used the cavitation-bubble design and was as equally ineffective above water as the original. The 4.5mm cartridge was effective to 55 feet underwater, and that varied based on the depth. The range decreased as the depth increased. The new design was eventually accepted by the Soviet Navy and entered service in 1971. It is believed that the Naval Forces of the Russian Federation still use this weapon today.
While the Soviets were developing the SPP-1, the United States was working on the design of their M1 Underwater Defense Gun for the US Navy combat swimmers. Much of the development was carried out at the Naval Surface Weapons Center Laboratory in Silver Springs, Md. In what appears to be an amazing coincidence of similarity, the original concept for the US weapon fired a lancejet round. This was a rocket-propelled round based on gyrojet weapons and projectiles. These had been developed commercially some years earlier, but were never taken up or adopted by the military. Like the Russians, the US military decided this round was too innovative, not to mention costly and totally inaccurate above ground, so the idea was scrapped.
The M1 designed the Mark 59 underwater ammunition as an attempt at a more conventional round. The Mark 59 ammunition was contained in a preloaded, stainless-steel, six-round cylinder. The cylinder was 5.5 inches long and was effectively a “pepperbox” configuration with each chamber acting as its own barrel. The six chambers contained a 4.25-inch, heavy-stabilized, tungsten-fin darts, which were propelled from the weapon by a captive piston when the gun was fired. With a muzzle velocity of 738 feet per second, the effective 32-foot range at a depth of about 60 feet was similar to the SSP-1. The frame, action, door assembly and cylinder were all made from lightweight alloys while the other parts were machined from stainless steel and the double-action trigger was made of nylon.
The M1 entered into service in 1970 and was not overly popular, mostly due to its bulky configuration. It was withdrawn from service in the 1980s and replaced by the Heckler & Koch HK P11 underwater pistol.
The HK P11 is one of the least-known weapons to emerge from Heckler & Koch’s factory in Germany’s Black Forest. For a long time H&K would not even acknowledge its existence, but recently some details have become available.
Developed during the 1970s to arm the Kampfschwimmer, the commando frogmen of the German Bundeswehr, this weapon has since been adopted by other NATO navies, including those of Italy, France, Norway, the Netherlands, UK and the US.
The P11 and the ammunition is somewhat bulkier than the SPP-1 Soviet counterpart, and just like the US M1 underwater pistol, it uses a detachable pepperbox cluster of five barrels, each factory loaded with a powder charge and a drag-stabilized, flechette-dart projectile. Each projectile is 117mm long and weighs 31 grams with a muzzle velocity of 351 fps.
The effective underwater range depends on the depth, but the maximum is about 50 feet. Above water, the effective range is quoted as being around 65 feet, and while the long and relatively heavy flechette can be lethal at longer ranges, accuracy is minimized by the flechette tumbling and yawing in flight. ASJ
For more information, on the MK1, by renowned war journalist Joe Trevithick, you can visit him here.
Editor’s note: Part II is we look at Underwater Rifles used by frogmen here.
Posted in History Tagged with: 269th combat diver, Andrew Young, B-V1-307 Underwater Handgun, German Kampschwimmmer, H&K P11, Navy SEALs, Russian diver, Russian Navy SPP-1, SEAL, spetnaz, US M1 Underwater Defense Pistol