# GP-25

The GP-25 Kostyor ("Bonfire"), GP-30 Obuvka ("Shoe") and GP-34 are a family of Russian 40 mm under-barrel muzzleloaded grenade launchers for the AK family of assault rifles. The acronym GP stands for Granatomyot Podstvolnyj, "under-barrel grenade launcher" in Russian, and was adopted by Soviet forces in 1978.

## Development

The development of a grenade launcher for the AKM assault rifle began in 1966 at the Central Design and Research Bureau of Sporting and Hunting Arms (TsKIB SOO). Development continued into the 1970s, and in 1978 it was accepted into service. The initial version was designated the BG-15 Mukha ("Fly"), and was mounted under the barrel of the AK-74 assault rifle. The main production version, the GP-25, has a different aiming system. The GP-30 was made lighter and the aiming system was redesigned and moved to the right.
GP grenade launchers are similar in appearance and fire the same Russian 40mm caliber ammunition. At the top of the barrel is the mounting hardware to attach the weapon to the underside of a rifle barrel, from which it is designed to fire. The GP barrel has a useful life of about 400 rounds.
The GP-30 first entered service in 1989, and is intended for use with the AK-100 series of assault rifles. The GP-30M is a grenade launcher of simplified model, consisting of a shorter 40mm rifled barrel in front of a basic trigger mechanism with minimal hand grip.
The current Izhmash-made version, the GP-34, has a further-redesigned sighting system located to the right side of the weapon and features the following advantages:
* Reliability: It is designed and tested specifically for the Kalashnikov assault rifles, fits such assault rifles directly without any adaptors or hand guard dismantling.
* Improved safety: The design prevents a round from moving within or falling out of the barrel, even if the muzzle is pointed down. The GP-34 features an additional mechanism (firing pin safety lever) to improve safety during loading.

### Variants

* GP-25.
* GP-30M.
* GP-34.
* ГП-25 (GP-25), GRAU index: 6Г15 (6G15), nickname «Костёр» (Kostyor, "Bonfire")
* ГП-30 (GP-30), GRAU index: 6Г21 (6G21), nickname «Обувка» (Obuvka, "Shoe")
* ГП-34 (GP-34), GRAU index: 6Г34 (6G34)

## Use

A grenade is first loaded from the muzzle, the weapon is aimed, and then the double-action trigger is pulled to fire. This fires the percussion cap at the base of the grenade which activates the nitrocellulose propellant inside the grenade body. The hot, expanding gas from the propellant is forced through openings in the base of the grenade that move it along the barrel and, at the same time, force the driving band to fit into the twelve grooves of the rifle. The rifling provides stabilizing rotation to the projectile. The grenade has a range of up to 400m.
* GP-25 sighting system.
* GP-25 seen from the front.
* Explanation on the use of the GP-25.

## Ammunition

GP grenade launchers fire multiple 40mm VOG-25 high-explosive fragmentation grenades, with a total range of 400 meters and an effective range of 150m. These Russian-Soviet 40 mm grenades are not compatible with Western 40x46mm grenades. Originally, the main grenade was the VOG-15 (7P17) fragmentation grenade, which has a lethal radius of six meters. Ammunition for the muzzle-loading GP-25 consists of a single piece containing propellant and charge, as opposed to the more traditional two-piece case and projectile design of comparable US 40x46mm ammunition used in breech-loading grenade launchers, such as the M203. This integral "caseless" design – with the propellant and primer contained in the base of the grenade – provides for when the grenade is fired nothing is left in the barrel, so the operator can load the next grenade.
A bouncing grenade, the VOG-25P, is also available. On impact, a small charge in the nose of the grenade explodes; this raises the grenade 50cm to 1.5m in the air, before an impact delay fuse causes it to detonate. The VOG-25P also has a lethal radius of six meters. The new generation VOG-M and VOG-PM ammunition, with an increased effectiveness of no less than 1.5 times, are now serially available.
Smoke grenades are also available. The original GRD-40 grenade was replaced by a series of grenades designed for use at different ranges. These are the GRD-50, GRD-100 and GRD-200 intended for use at 50, 100 and 200 meters respectively. They are capable of producing a 20 cubic meter cloud of smoke that lasts for one minute in winds of up to five meters per second. A tear gas grenade called Gvozd ("Nail") and a stick grenade are also available.

### Ammunition data

| Version | Fuse arming range | Fuse self-destruction time | Weight | Charge |
| VOG-25 | 10–40 m (33–130 ft) | 14–19 s | 250 g (0.55 lb) | 48 g of A-IX-1 explosive |
| VOG-25P | 10–40 m (33–130 ft) | 14–19 s | 278 g (0.61 lb) | 37 g of TNT |
| GRD-50/100/200 | 10–40 m (33–130 ft) | 14–19 s | 265 g | 90 g |

## Users

* Angola
* Algeria
* Botswana
* Bulgaria: Made under license by Arsenal AD as the UBGL and the UBGL-1.
* Burundi
* Congo-Kinshasa
* Cyprus
* Georgia: Made by STC Delta.
* Greece: Used for the AK-74M.
* India
* Indonesia: Mobile Brigade Corps
* Iran : Used by IRGC
* Lithuania: Lithuanian Armed Forces
* North Korea
* Pakistan
* Russia
* Serbia: Made under license by Zastava Arms as the PBG – 40 mm and the PBG 40 mm M70.
* North Macedonia
* Syria: Uses both GP-25s and GP-30Ms.
* Ukraine
* Vietnam