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GP-25 Kostyer

40-mm underbarrel grenade launcher

GP-25 grenade launcher

The GP-25 was the first operational Soviet underbarrel grenade launcher

Country of origin Soviet Union
Entered service 1978
Caliber 40 mm
Cartridge 40x103 mm
Weight (empty) 1.5 kg
Cartridge weight 0.26 kg
Length 323 mm
Barrel length 205 mm
Muzzle velocity 76 m/s
Practical rate of fire 4 - 5 rpm
Magazine capacity 1 rounds
Sighting range 400 m
Range of effective fire up to 250 m
Maximum range 400 m


   Designed during the Cold War by the TsKIB SOO design bureau, the GP-25 Kostyer ("Bonfire") was the first underbarrel grenade launcher fielded by the armed forces of the Soviet Union. In fact, it was also their first operational grenade launcher of any type.

   The Soviet Union began the development of an underbarrel grenade launcher in 1966. This was during the time in which the US Army's GLAD program (which soon resulted in the M203) was taking place, so it is very likely that Soviet interest in such a weapon stemmed from their observations of GLAD. Though also like the GLAD program, the initial product of its Soviet counterpart --- the BG-15 Mukha ("Fly") --- was deemed unsatisfactory. As a result, work continued well into the 1970s, but the effort paid-off when the resulting GP-25 Kostyer was approved for general service by the Soviet Army later in that decade. The GP-25 entered operational service in 1978, though at the time the Western Bloc was unaware that their latest crop of grenade launchers had a secret Soviet rival.

   Looking more like a pipe assembly than a weapon capable of wounding many personnel with one shot, the GP-25 consists of a wide, short barrel, a mounting bracket with a conspicuous sighting device on the left side, a very large trigger group with a straight-pull trigger, and a short and stubby pistol grip. The GP-25 is made with a variety of finishes, but they are usually entirely black in color. The barrel is rifled, with conspicuously deep grooves.

   The GP-25 is muzzle-loaded, rather than being breech-loaded like most other grenade launchers. Grenade rounds loaded into the weapon are properly seated once they snap into a spring catch, which also has the benefit of preventing the round from falling out when the weapon is pointed downward or turned rapidly. In the event that the weapon must be unloaded, a push-out extraction system is built into the left side of the weapon. Unlike the M203, the GP-25 has a safety mechanism, which is a decidedly important consideration in a weapon capable of potentially killing an entire infantry squad. The barrel life of the GP-25 is relatively short, at 400 rounds.

   Also unlike the M203, which requires the weapon its mounted under to have a sight added on top, the GP-25 has its own sights. Being located on the left side of the weapon (as previously mentioned), the user can only aim the GP-25 accurately from the right shoulder. Aiming the GP-25 effectively from the left shoulder requires extensive experience, and more than a little bit of guesswork.

   The GP-25 cannot be used as a standalone weapon, and must be attached to a larger firearm; usually an assault rifle or a carbine. It is most commonly seen mounted on AKM and AK-74 series weapons. However, a standalone version was developed later, in the form of the RGM-40 Kastet ("Brass knuckles").

   The GP-30 Obuvka ("Footwear") is an improved version of the GP-25. It was developed as a lighter, and cheaper alternative to the GP-25, as an economy measure. Another important change was the replacement of the original sights, which gave way to a new improved sight system, mounted on the right side of the weapon (rather than the left side); it is reportedly much easier to aim, but also no longer provides sighting for indirect fire.

   Although the GP-25 launches the same bore of grenade as its Western counterparts, it is a caseless round that eliminates the need to for a casing extraction mechanism. The caseless 40 mm grenade is launched in a very similar manner to a mortar shell. The propellant charge is loaded into the projectile itself, and is ignited when the firing pin strikes a percussion cap (another interesting throwback to earlier firearms, along with the muzzle-loading system) at its base. The recoil of the GP-25 is apparently stronger than that of its Western 40x46 mm counterparts, given that rifles fitted with this weapon also receive a rubber shock absorber on their buttstocks.

   The GP-25 may be fired from standing, kneeling, or prone positions. It may also be fired at high angles like a mortar from a sitting position, with the butt of the main weapon braced against the ground.

   Each solider, equipped with the GP-25, carries 10 grenades. A wide variety of different grenades were developed for the GP-25, all of which are fuzed to self-destruct 14 seconds after launch, if they have not impacted. The primary Russian-made variants are described below.

   The VOG-25 is a basic High Explosive Fragmentation (HE-FRAG) round, with a weight of 255 g and a 48 g high-explosive filler. When launched, it arms itself 10-40 meters away from the shooter. The grenade detonates on impact. Lethal blast radius is up to 7 meters. This grenade it effective against personnel in the open, as well as softskin vehicles and light structures.

   The VOG-25P is another HE-FRAG grenade, with 272 g overall weight and a smaller 37 g HE filler, but it has a nasty twist; rather than exploding on impact, a tiny precursor charge in the nose of the VOG-25P detonates and launches the main 37 g charge into the air, where it detonates 0.5 to 1.5 m off the ground. As a result, it produces a devastating shockwave and shrapnel fan, which are extremely lethal against standing personnel over a very broad area, lying prone, or even behind "cover", not unlike the much-feared rebounding landmine (also called "Springmines" and "Bouncing Betties"). The VOG-25P is not as effective on impact with vehicles or structures --- but its a different matter if one is fired *into* the midst of these targets.

   The VOG-25 TP round is a training version of the basic VOG-25, and launches an inert projectile that doesn't explode. It has the same weight and ballistic trajectory of the real thing.

   The GRD-40 smoke grenade with a weight of 260 g, that emits a billowing and opaque smoke cloud for 60 seconds following impact. The smoke cloud expands rapidly, screening a 10-square-meter area after 1 second, a 20-square-meter area after 2 seconds, and a 25-square-meter area after 3 seconds. Later production GRD-40 grenades emit smoke that also obscures infrared optics.

   The GZH-40 is a stun grenade, which detonates on impact with a relatively less-lethal explosion, but one which is loud and bright enough to briefly dazzle and disorient offenders.

   The GS-40 "Gvozd" ("Nail") round is similar in effect to the GRD-25, but emits Agent CS tear gas instead of smoke.

   Many equivalent grenades are manufactured in Bulgaria by Arsenal, and also some that are rather unique compared to the Russian range of 40 mm grenades. These are described below.

   The RLV-AD is technically an HE grenade, but it is designed for use against enemy divers. It is a 260 g projectile intended to be launched into deep water, sink to a depth of 5 m, and then detonate, essentially making it a small depth charge. It is capable of causing casualties up to 15 m when detonating underwater, and stunning divers at up to 30 m. The mass of the RLV-AD's explosive filler and whether or not it can be used like a regular HE grenade have not been published.

   The RLV-ILL-WS is a 250 g illumination round, which parachutes slowly to the ground from and altitude of 185 m. Its illumination candle activates at the same time, emitting a brilliant white with an intensity of 90000 candela, which illuminates a broad area for as long as the round remains airborne.

   The RLV-TB is a 250 g thermobaric round, bearing an unspecified quantity of filler. Upon impact, a small HE bursting charge inside the round detonates, which serves both to release and disperse the TBC-2 thermobaric compound inside. This compound is volatile enough to detonate on contact with air as it expands and thins, resulting in a fuel-air explosion. The effects of the blast are extreme heat and a lethal shockwave, making the RLV-TB extremely effective against personnel, softskin vehicles, and light structures over a wide area, as well as heavy structures and pillboxes, if the grenade can be successfully launched into them.

   The early operational service of the GP-25 in the Soviet Army was exceptionally low-key, and the West didn't even become aware of its existence until the middle of the Soviet Occupation of Afghanistan, in 1984. The GP-25 and GP-30 have since been used in many conflicts throughout the world, notably in the Yugoslav Civil War, numerous skirmishes between former Soviet States, and the Afghan War.

   Surprisingly, the GP-25 and GP-30 did not proliferate as widely as the US M203, despite being designed primarily for the AK-74. The known operators of this weapon include Russia, Afghanistan, Algeria, Angola, Azerbaijan, Bulgaria, China, Cyprus, the Democratic Republic of Congo, Ethiopia, Georgia, India, Lithuania, Moldova, North Korea, Pakistan, Panama, Serbia, Ukraine, Uruguay, and Vietnam.

   The GP-25, along with its variants and derivatives, are still manufactured in Russia, Bulgaria, Georgia, and Serbia. Due to their long service, large-scale proliferation, and enduring production, they are likely to remain in operational service far into the foreseeable future.




   BG-15 Mukha: Pre-production version of the GP-25. Only saw limited service.

   GP-25 Kostyer ("Bonfire"): Initial production model, as described above.

   GP-30 Obuvka ("Footwear"): Improved version of the GP-25, adopted in 1989. It was developed as a lighter, and cheaper alternative to the GP-25, as an economy measure. Another important change was the replacement of the original sights, which gave way to a new improved sight system, mounted on the right side of the weapon (rather than the left side); it is reportedly much easier to aim, but also no longer provides sighting for indirect fire.

   GP-34: Further improvement of the GP-25/30 design, which replaced them in production and development. Manufactured in Russia by IZHMASH.

   RGM-40 Kastet: Standalone version of the GP-25/30.

   PBG 40mm M70: GP-30 built under license in Serbia.

   UGBL: GP-25 built under license in Bulgaria.

   BGP40: GP-25 built under license in Yugoslavia.


Similar weapons


   M203: This US underbarrel grenade launcher was the first successful weapon of that type to see operational service. It also fires a 40-mm grenade, but this round uses a 40x46 mm casing. The GP-25 was inspired by the M203.

   ARDE: Indian underbarrel grenade launcher similar in configuration to the M203, but with sights more like those on the GP-25. Chambered in the 40x46 mm round.

   GL 5040: Swiss 40x46 mm underbarrel grenade launcher for use on the SIG SG 550 assault rifle. There is a shorter version called the GL 5140 for use on the SG 552 and SG 553 carbines.

   IMC-40: Columbian 40x46 mm underbarrel grenade launcher for use on the Galil assault rifles, similar in design to the M203.

   QLG-10: Chinese 35-mm underbarrel grenade launcher for use on the QBZ-95 assault rifles. Launches a caseless 35 mm grenade, similar to the 40 mm grenade for the GP-25/30.

   HK79: German 40x46 mm underbarrel grenade launcher based on the HK69 standalone weapon, for use on the G3 series of rifles.

   AG36: German 40x46 mm underbarrel grenade launcher for use on the G36 series of rifles.

   AG-C/EGLM: German 40x46 mm underbarrel grenade launcher based on the AG36, for use on AR-15 series rifles. It is also manufactured under license in the UK as the L17A1 and L123A2 UGL.

   More types of underbarrel grenade launchers are described on the M203 page.



   Article by BLACKTAIL

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GP-25 grenade launcher

GP-25 grenade launcher

GP-25 grenade launcher

GP-25 grenade launcher

GP-25 grenade launcher

GP-25 grenade launcher

GP-25 grenade launcher

GP-25 grenade launcher

GP-25 grenade launcher

GP-25 grenade launcher

GP-25 grenade launcher

GP-25 grenade launcher

GP-25 grenade launcher

GP-25 grenade launcher

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