AB-5.45 and AB-7.62

 AB-5.45 and AB-7.62 are assault rifles, chambered with 5.45x39mm and 7.62x39mm rounds respectively. AVB is a battle rifle, chambered with 7.62x54R round, LCZ B20 is its 7.62x51 modification. Weapons automatics is based on a delayed blowback and rear sear, which is more typical for submachine guns, machine guns and automatic guns than assault rifles and automatic rifles. 

The shot is made when the shutter is open. Weapon automatics' moving parts before firing are in the rear position, and the cartridge is not in the unlocked chamber. After pressing the trigger, locking assembly begins to move forward under the pressure of the return spring, and reforwards the cartridge into the chamber. When an assembly comes to its most forward position, the locking lever locks the barrel and strikes at the shutter located in the skeleton of the drummer, that skewers the capsule holder. 

The shot is made. Bottom part of sleeve rests on having a cup of free lift shutter striker, which at this moment is not tightly coupled with the barrel. Striker with the sleeve is moved back and acts as the frame, which begins to move back and affects the skeleton of the shutter, and then on the locking lever, rests against a ledge receiver. The valve uncouples with the receiver, the sleeve extracts and the compression spring returns.

Baryshev AB-762 and AVB-762 assault rifles (Russia)

Caliber: 7,62x39 M43, 7,62x54R or 7,62x51 NATO

Overall length (stock open / folded): 960 / 710 mm, 1000/ 750 mm

Barrel length: 415 mm, 455 mm

Weight, empty: 3,6 kg, 3,9 kg

Rate of fire: 750 rounds per minute, 750 rounds per minute

Magazine capacity: 30 rounds,10 or 20 rounds

Anatoly F. Baryshev designed its original delayed-blowback action in early 1960s. His design was very unusual for the time, mostly in the fact that it wasa private effort - a thing, rarely encountered in Soviet Union. Nevertheless, Baryshev managed to find some support in the higher ranks of Soviet Army.Several prototypes were built and tested. New action showed its major advance - a significant decrease in felt recoil, but otherwise it proved to be unreliableunder harsh conditions and inaccurate in single shots. Army rejected the design,but Baryshev and his supporters had been trying to promote this design till latenineties. 

During early 1990s Baryshev also cooperated with Czech company LCZ Group, which manufactured several prototype rifles in calibers such as 7,62x39 and 7,62x51. These rifles were displayed on several military exhibitions, butfound no buyers, and apparently were dropped by late 1990s. In the mean time, Baryshev designed an unique large handheld caliber weapon, which fired12,7x108mm heavy machine gun of 30x25B grenade ammunition (change of caliberre quired change of barrel, magazine and bolt). 

Because of Baryshevrecoil-reducing action, this weapon can be fired from the shoulder, but it stillhad all drawbacks of all other Baryshev weapons - that is, insufficient reliability and insufficient accuracy in single shots, and accurate burst fire was also all but impossible from such large-caliber but lightweight gun with limited magazine capacity. It must be noted that Baryshev system allowed to build lightweight fully automatic weapons in powerful "rifle" calibers such as 7,62x54R or 7,62x51, which were controllable in full automatic fire; butt his was the only significant advantage of the system over other, more conventional systems.

Baryshev action is a delayed-blowback system which is fired from open bolt only. Bolt group consists of four parts - bolt with tilting head, inertia piece and locking lever. When gun is fired, bolt group is released and goes forward at once, stripping a fresh cartridge from magazine. At the end of loading cycle, bolt with its head was stopped at the breech, while inertiapiece still moved forward, rotating the locking lever and bolt head. The pivoting locking lever struck the firing pin, and fired the cartridge. 

Recoil of the shot tried to pivot the bolt head, but this movement was resisted by the mass and velocity of the inertia piece. Once the inertia piece was stopped and its movement reversed by the blowback action of the cartridge, it turned the locking lever to disengage the bolt from receiver. 

Once bolt is released, entire bolt group is moved back under residual pressure in the chamber. This soundscomplicated as is, and the system never impressed anyone other than fewhigh-ranking officers in Soviet army. 

Korobov TKB-408 assault rifle (USSR)

Caliber: 7.62x39mm M43

Action: Gas operated, tilting bolt

Overall length: 790 mm

Barrel length: n/a

Weight: 4.3 kg

Rate of fire: n/a

Magazine capacity: 30 rounds

The TKB-408 assault rifle has been developed by designer German A. Korobov by 1946. This weapon has been designed in Tula, for 1946 Soviet Army trials for anew assault rifle. Usually claimed as a first military-type automatic rifle of bullpup configuration, this weapon, in fact, has been preceded by several designs that appeared during the WW2 in Great Britain and USSR (i.e. Korovin7.62mm experimental assault rifle of 1945). This weapon was tested by Soviet Army commission in 1946-47, but was found unsatisfactory; eventually, trials were won by Kalashnikov AK rifle.

TKB-408 is gas operated, locked breech weapon that uses vertically tilting bolt to lock the barrel. Cocking handle is located at the left side of the weapon,above the wooden handguard; it does not reciprocate when gun is fired. Gun fired in full automatic mode and in single shots. Firing mode selector is located at the left side of receiver, above pistol grip. 

Separate safety switch is located within the triggerguard, in front of the trigger. Ejection port is located at the right side of weapon, above the magazine, and has flip-down dust cover.There were no provisions for firing from the left shoulder. TKB-408 used proprietary magazines, made from sheet steel. each magazine held 30 rounds and had a forward projection that entered the magazine lock, located at the bottom of pistol grip. Weapon was mostly made of stamped steel, with wooden buttstock and handguard.

ADS dual-medium / amphibious / underwater assault rifle (Russia)

Caliber: 5.45x39mm 7N6 / 7N10 / 7N22 for above-water fire and 5.45x39 PSP or PSP-U for under-water fire

Action: Gas operated, rotating bolt

Overall length: 660 mm

Barrel length: 415 mm

Weight: 4.6 kg (with integral 40mm grenade launcher)

Rate of fire: 600-800 rounds per minute

Magazine capacity: 30 rounds

For several decades, Soviet and then Russian combat divers and Naval commando units were armed with special weapons for underwater combat, including the SPP-1 pistol and APS underwater assault rifle. The main drawback of these weapons is that their effectiveness (and life expectancy) for use above the water is severely degraded compared to standard 'above water' weapons. Therefore, combat divers and other Spetsnaz units, when engaged in amphibious operations (below the water and above), had to carry on the mission two types of weapons - one for underwater use and another for use when on shore or on board of enemy surface vessels. 

The first known attempt to produce a single weapon which could be effectively used either below or above the water was the ASM-DT experimental 'dual-medium' or amphibious assault rifle, developed in Tula in around 2000. The main problem with ASM-DT was that it still had to use extremely long, specially designed underwater ammunition when submerged, which necessitated overly long receiver, complicated magazine well of adjustable size and two types of magazines. This was found unsuitable for combat use, and further development commenced at the famous arms development facility KBP (Instrument Design Bureau) in Tula. By 2005, design team at KBP has successfully developed effective underwater ammunition which retains the compact size of the standard issue 5.45x39 7N6 ball (as well as 7N10 and 7N22 AP) rounds, and thus can be loaded and fired from standard AK-74-type box magazines, and, more importantly, fired from the same chambers and barrels that would accept the 'above-water' 7N6 ammunition.

This new cartridge is known as 5.45x39 PSP, and is externally similar to standard 5.45x39 ammunition except that it has a different bullet shape. Internally it differs in having a long bullets, which has specially calculated shape and protrudes back into the cartridge case all the way to the bottom, with overall bullet length being about 53mm (2.1 inch), compared to overall cartridge length of 57mm. There are two types of PSP ammunition, the 5.45 PSP (combat ammunition) with hardened steel projectile weighting 16 gram (muzzle velocity on air about 330 m/s) and 5.45 PSP-U (practice / training ammunition) with bronze projectile weighting 8 gram (muzzle velocity on air about 430 m/s). Effective range with PSP ammunition varies from 25 meters at 5 meters depth to 18 meters at 20 meters depth; effective range of the PSP-U training ammunition when below teh water is about 2 times shorter. 

Having settled on new ammunition, designer at KBP commenced work on the new weapon, well suitable for both surface and underwater combat. This new rifle was designated as ADS (АДС - Автомат Двухсредный Специальный - Avtomat Dual-medium, Special).They used the A-91M bullpup assault rifle as a starting point, retaining its bullpup layout, gas operated action with rotary bolt locking and forward ejection through the short tube running above and to the right of the barrel. Some parts of the weapon were necessarily redesigned and materials revised to work reliably when submerged in water, gas system was modified with addition of the environment selector ("air / water"). Integral 40mm grenade launcher (which fires VOG-25 type 'caseless' grenades using additional front trigger inside the trigger guard) is fitted with removable barrel which can be removed when it is not needed by the mission profile.

Muzzle of the barrel is threaded to accept muzzle brake / compensator, tactical silencer or blank-firing adapter. Rifle is fitted with adjustable iron sights, and an integral carrying handle is provided with Picatinny type rail on the top to accept various day and night optical sights. The ADS can fire any standard issue 5.45x39 ammunition (ball, tracer, AP) when above the water, with accuracy and effectiveness similar, if not better than of AK-74 / AK-74M general issue assault rifle. When submerged and loaded with 5.45 PSP ammunition, ADS outperforms APS underwater assault rifle in terms of accuracy and ease of handling.

As of now (mid-2009), the ADS is said to be under extensive field trials by undisclosed units of Russian Naval special forces. If adopted, it will replace APS underwater weapons and, possibly, some AK-74M general issue assault rifles in service with Russian Navy special operation units and other Russian special forces, which might be engaged in underwater operations (security, counter-terrorism in the sea, etc).

ASM-DT

Caliber: 5.45 mm  (5.45x39 forabove water firing and 5.45mm special underwater ammunition forsubmerged firing)

Action: Gas operated, rotating bolt

Overall length: n

Barrel length: n

Weight: kg

Rate of fire: ~600 rounds per minute

Magazine capacity: 30 rounds (for above waterconfig) or 26 rounds (for underwater config)

In mid-1970s, Soviet Navy adopted an underwater APS assault rifle for its combat divers, to provide underwater security against enemy frogmen and specially trained sea animals (i.e. dolphins). The APS, while successful in its narrow niche, had its set of inherent flaws, so, during the late 1990s,a severely modified version of it appeared in Tula, in the form of the experimental ASM-DT “dual medium” amphibious assault rifle.

The key improvement of the ASM-DT is that it uses a 5.45 mm rifled barrel with relatively shallow rifling, which allows to fire both standard 5.45 x 39 spin-stabilized ammunition, and modified underwater hydrodynamically stabilized ammunition, which is also based on 5.45 x39 case, with long projectile of about 5.4 mm in diameter. To achievethis, the magazine housing of the ASM-DT is fitted with a sliding magazine catch, which can be positioned at the rear of the long magazine port to hold the deep underwater magazines, or in the middle of the magazine port to hold the relatively shallow (front to back)AK-74 magazines. 

In the latter mode, the rear, unused part of the magazine housing is closed by a spring-loaded dust cover. To avoid problems with the remaining water in the barrel when firing the 5.45 x39 in air, the chamber has special grooves that lead from the chamber forcing cone forward, into the rifling grooves. When the standard 5.45mm cartridge is fired, a small amount of powder gases run through the grooves ahead of the bullet, effectively blowing the remaining waterout of the barrel. The rest of the action is similar to the APS, butthe muzzle is fitted with AKS-74U-style muzzle device / flash hider.The overall performance of ASM-DT with underwater ammunition is similar to the APS, while in air and with standard 5.45 x 39 ammunition, it is roughly on par with the AKS-74U and greatly out performs the APS.

A-91 assault rifle (Russia)

Caliber: 7.62x39mm and 5.56x45mm NATO

Action: Gas operated, rotating bolt

Overall length: 660 mm

Barrel length: ??

Weight: 3.97 kg empty (with integral grenade launcher)

Rate of fire: 600-800 rounds per minute

Magazine capacity: 30 rounds

The A-91 bullpup assault rifle (also known as A-91M) was developed during the 1990s by KBP (Instrument Design Bureau) in Tula, as an offspring of the A-91 family of compact assault rifles described above in the 9A-91 article. 

While the A-91 retains the basic gas-operated, rotating bolt action and a trigger unit design from 9A-91, it features a bullpup polymer housing, with an integral 40 mm single-shot grenade launcher mounted under the barrel. The earliest prototypes of the A-91 bullpup were fitted with the grenade launcher above the barrel, and with a front vertical foregrip; current models are fitted with the underbarrel launcher, which also serves as a forearm. 

The A-91 features a forward ejection system, initially developed in Tula by designers like Afanasiev during the early 1960s. In this system, the ejection port is located above the pistol grip, and points forward. Extracted cases are fed from bolt head through the short ejection tube to the ejection port, and fall out of the gun well clear of the shooter's face, even when firing from the left shoulder. As for now, the A-91 is made in small number and, probably, is used by some elite law enforcement units in Russia; it is also offered for export and domestic military and police sales.

The controls include double triggers (front for grenade launcher, back for rifle), and a large fire mode / safety lever at the right side of the receiver, above the magazine housing. The rifle trigger is fitted with an additional automatic trigger safety. The charging handle is located above the receiver, under the carrying handle, and is easily accessible for either hand.

The sights include a front post, mounted on a high base, and an aperture rear, adjustable for range, which is mounted on the integral carrying handle. The top of the carrying handle is shaped as a Weaver-type rail, and can accept a vide variety of scopes and sights. Folding grenade launcher sights are mounted at the front of the barrel.

Originally developed for 7.62 x 39 ammunition and standard AK-pattern magazines, the A-91 bullpup is now also available in 5.56 x 45 NATO chambering, which uses proprietary 30 round polymer magazines.