A new generation of AGLs: within only a few decades the Automatic Grenade Launcher (AGL) has leapt from the concept stage to becoming a widely accepted and valued infantry support weapon, providing the foot soldier with a highly effective area fire suppression system.
The AGL must be differentiated from the smaller, rifle-mounted grenade launchers. The latter, usually involving single-shot, rifle-mounted barrels, have considerably less range than the higher velocity grenade rounds fired by the AGLs, although the grenade warhead payloads involved are usually comparable. In some instances the low velocity launchers have attained a fair degree of sophistication so they cannot be totally ignored. However, the next generation of high velocity AGLs promises to be even better in all-round terms than the initial generation, thanks to two main factors, namely reductions in weight and the introduction of electronic fire control and fuzing.
Worth mentioning here is the M-203 PI series of grenade launchers which are adaptable to almost any infantry assault weapon and folding stock pistol. Although not high-velocity launchers, they are the design most effective in tight spaces. The R/M Equipment 40 mm launcher system, for example, can be easily swapped between a rifle and pistol unit in mere moments, thereby giving a fire squad on the move maximum capabilities.
Before consideration is given to AGL details, some differentiations between the various types of spin-stabilised grenades have to be established. Both high and low velocity examples can be divided into two main groupings -- Eastern and Western Bloc. There are few similarities between the two.
Eastern Bloc models have calibres of 30 mm (high velocity) or 40 mm (low velocity). The 40 mm low velocity, rifle-launched grenades utilise an internal charge propulsion system for launching/ firing and also to impart spin stabilisation during flight. The high velocity grenades utilise a propelling charge in a short cartridge case.
Western Bloc grenades are 40 mm in diameter for both high and low velocity models, their main difference being in the propellant charge size and the cartridge case involved. Low velocity grenades have a cartridge case 46 mm long (hence 40 x 46 mm) and their maximum effective range is approximately 400 metres. The case for high velocity, belt-fed grenades is 53 mm long (40 x 53 mm), containing more propellant and so producing a much higher muzzle velocity (from 240 to 242 m/s at the muzzle) to ensure the maximum range can be as much as 2200 metres.
The Western Bloc 40 mm grenades employ a launching principle based on a WWII German ballistic development known as the high-low pressure system. For this a small but powerful propellant charge is located and detonated within a small stoutly constructed chamber in the base of the cartridge case. On ignition the resultant high pressure is allowed to vent at a controlled and relatively slow rate through small, carefully designed vents into the case's main chamber. The resultant pressures inside the case therefore become much lower and manageable but are still capable of launching the grenade itself. Recoil forces and stresses can thus be much less than those for a conventional cartridge-based firing system, while the case itself can be lightly and economically constructed using aluminium or thin steel -- some training rounds have plastic cases. Rifling within the AGL barrel imparts the spin stabilisation necessary during flight.
These simple outlines cannot include every type of spin-stabilised grenade currently available, for, as we shall see, a 25 mm grenade round is in the offing, and several other types, including a Chinese 35 mm grenade from Norinco, are available. However, the above covers the main principles.
The distinction of being the first active service AGL goes to the Russian AGS-17 Plamya (Flame). Although it entered Eastern Bloc service in 1975, its combat debut and subsequent exposure to foreign observers was delayed until during the early Soviet campaigns in Afghanistan. Its appearance created quite a stir as development work in the USA had been in progress on a similar type of weapon (that would emerge as the 40 mm Mk 19) since the late 1960s. The original intention was to produce an AGL for the US Navy, to be utilised during riverine operations such as those conducted in Vietnam. The arrival of the AGS-17 as a land service fire support weapon therefore caused a drastic reassessment of the new AGL's capabilities.
In design terms (but not in appearance), the 30 mm AGS-17 and the US 40 mm Mk 19 have much in common. Leaving aside the calibres, both are belt-fed weapons capable of fully automatic fire and both can be tripod-mounted for infantry deployments. Each relies on the blowback principle for operation. They have similar cyclic rates of fire, between 300 and 400 rds/min, although short bursts are usually the order of the day. Both are still in series production and remain available in the defence marketplace, and have been
licence-produced, the AGS-17 in China (by Norinco) and Iraq, while the Mk 19 has been manufactured in South Korea (Daewoo) and Egypt. At one time the Mk 19 was also produced in Israel. Once manufactured by Saco Defense, the Mk 19 is currently marketed by General Dynamics Weapon Systems.
While grenades fired from the AGS-17 can reach 1700 metres, those from the Mk 19 reach 2200 metres. In practical terms these maximum range differences matter little for both AGLs are usually tactically employed only up to about 1500 metres. Attempting to utilise the maximum possible ranges usually results in poor accuracy (or until recently at least) due to the still relatively low muzzle velocities involved. Side winds or other influences encountered during the long time of flight, plus the high curved trajectories involved, can thus result in trajectory and on-target variables that, as will be outlined, reduce the efficiency of the grenades themselves.
One of the main problems involving the AGS-17 and Mk 19 AGLs is their weight. The AGS-17 gun/launcher alone weighs 18 kg; the Mk 19 is even heavier at 35.3 kg. To these loads have to be added tripods, ammunition boxes and sights, so shifting these early models of AGL in the field can be quite a task. Hence the frequent redirection of such AGLs to mountings based on vehicles (including armoured vehicles), helicopters or light naval vessels, although tripod-mounted field applications still remain important.
Since the inception of the AGS-17 and Mk 19 they have been joined by many others. AGLs have been developed (although not necessarily introduced to series production) in such nations as South Africa (the Vektor 40 mm AGL Striker), Spain (the Santa Barbara 40 mm LAG 40 SB-M1), Singapore (40 mm 40AGL), Germany (the 40 mm Heckler & Koch GMG -- see below), Romania (Romarm 40AGA, firing a different 40 mm grenade family to those produced elsewhere), Pakistan (Daudson Armoury 40mm AGL), Poland (Zaklady `Tarnow' 40 mm GA) and Turkey (Roketsan 40 mm Automatic Machine Gun). Other such systems are no doubt under development elsewhere. All those already mentioned above fall within the heavyweight bracket.
The AGL weight factor can be tolerated by most conventional field forces, but for self-contained special or airborne units it becomes far more significant, especially as several soldiers may be needed to serve the weapon, especially during moves. As a result one of the more recent AGL developments has been to introduce much lighter designs, reducing the number of personnel necessary to carry and fire the weapon. Once again, the Russians were to the forefront, for by 1995 the first examples of the 30 mm AGS-30 were being displayed (under the design designation of TKB-722K) by the KBP Instrument Design Bureau.
The AGS-30 is based around the earlier AGS-17 but with virtually every component either replaced by something lighter or omitted altogether -- the number of AGS-30 components has been reduced by some 40 per cent compared to the AGS-17. AGS-30 weight is reduced to a claimed 16 kg, and that includes the unusual lightweight tripod with its single forward-facing leg. Recoil stresses are stated to be low, thanks mainly to a highly efficient buffering system. The ammunition fired is the same as for the AGS-17 so the maximum range remains up to about 1700 metres. The sight is also the same as before, while the cyclic fire rate is up to 400 rds/min.
When the AGS-30 first appeared it was announced that it would replace the AGS-17 in production and service. That has yet to happen, but the AGS-30 was the first of many lightweights (although the term remains relative). By the end of the 1990s other lightweight AGLs were known to be in development in several countries and the first of them have appeared.
One of them, still utilising standard Eastern Bloc grenades, is the 30 mm Rag-30 marketed by Technopol of the Slovak Republic. The Rag-30 has several unusual design features that combine to produce a ready-to-fire and loaded weight of just 13.2 kg, so the weapon can be readily carried and served by a crew of one. Among the design features are a five-round vertical box magazine, a light bipod and a rudimentary folding butt stock. Cyclic rate of fire is 350 rds/min although burst length is restricted by the limited magazine capacity. One nice touch is a folding carrying handle on the side of the box magazine, so the compact Rag-30 can be easily carried at the point of balance.
If the Rag-30 is light, the potential weight of another recent arrival is lower still. This is the 40 mm Super Light Weight Automatic Grenade Launcher (SLWAGL) from Singapore Technologies Kinetics. With this advanced and slim design the belt-fed gun/launcher currently weighs in at around 14 kilograms, although it is intended that the final in-production model weight will be similar to that for a general purpose machine gun, about twelve kilograms or perhaps less.
This low weight is achieved by the incorporation of a locally developed Recoil Mitigation System that reduces the usual recoil forces considerably. Many SLWAGL components will then be subject to less stress and their weight can be reduced to a minimum by the introduction of lightweight materials, including some tungsten alloys. The Recoil Mitigation System is based on the soft recoil (or `out of battery') principle with which case ignition is delayed until the mass of the weapon moves to the forward position. Overcoming much of the recoil impulse by the forward-moving mass thus reduces many of the rearward-directed forces produced on firing, the forward mass being further increased by the closing of the heavy bolt.
Another AGL being produced with reduced weight in mind is the German 40 mm GMG (grenade machine gun) Light from Heckler & Koch. This is a development of the standard Heckler & Koch GMG that first appeared in fully developed form during 1995. At that time the GMG was designed with the needs of the German armed forces in mind, but the financial fall-out from the reunification of the former East and West Germanys meant that funding for local GMG procurement had to be terminated.
Although it has demonstrated high levels of reliability under all manner of environmental conditions, the GMG has yet to meet with sales success, one reason no doubt being its complete system weight (with tripod, softmount, etc) of 56.1 kg, or 75.5 kg with a belt of 32 rounds. With the GMG Light, the gun/launcher weight is reduced slightly to 26.5 kg (as compared to 28.8 kg) while a lightweight tripod is introduced and the softmount eliminated. These innovations bring the ready-to-fire weight with a 32-round belt down to 51.9 kg, still a significant load but much lower than for the original GMG.
It is understood that a lightweight AGL is under development in South Africa by Milkor, already responsible for the highly successful 40 mm (low velocity) MGL grenade launcher with its six-round revolving cylinder. No details of this development had been released at the time of writing.
The AGL has not found universal acceptance. Many observers have noted that grenade on-target performance can be limited, thanks mainly to the small warheads contained within the grenades fired. Offensive warheads can vary from high explosive fragmentation to dual purpose (anti-personnel/ anti-armour) but they are limited in their performance by the space and weight limitations imposed by the 30 and 40 mm calibres and their mechanical impact fuzes.
On impact, much of any conventional grenade warhead's effectiveness is reduced by detonating next to the ground or some other surface, thereby limiting the fragment spread and lethal potential. At best, the lethal radius of any explosive grenade warhead is about five metres. One Eastern Bloc grenade, the 30 mm VOG-25P, partially overcomes this drawback by introducing a small upwards-propelling charge that functions on impact to lift the grenade to a height of about one metre above the ground. The main fuze then functions to scatter the resultant fragments and blast over a wider radius than possible with pure impact fuzes.
Rather than follow this `bouncing' path, Western designers have decided to take another route. Many of the observed drawbacks of the small grenades can be overcome if they can be placed on or close to the required target. This includes air bursts above the target that can increase the lethal radius to as much as ten metres. However, to accurately place air bursting grenades some form of fire control better than the usual simple iron sights and visual range estimation is necessary.
One of the first forays into this territory was demonstrated by the 40 mm Striker/CG40 AGL system (Striker for North American markets and CG40 in Europe). Very much an international venture, the Striker/CG40 is based around the latest development of the US General Dynamics Weapon Systems' 40 mm Mk 19, although visual and internal resemblances to the original Mk 19 series are few. The Striker/CG40 gun/launcher is much reduced in weight to 18 kg, thanks to the introduction of lightweight materials, and introduces measures such as firing from a closed bolt to enhance accuracy.
The Striker/CG40 is allied with an electronic fire control system originally produced by Computing Devices Canada as their Lightweight Video Sight. This involves a video-based vision and sighting display, with image intensification for use at night, and an eye safe laser rangefinder accurate up to 2000 metres. Placing the sight and lasing a target results in the correct range being calculated and the correct angle of super elevation is introduced into the sight unit. As super elevation angles can be pronounced at the longer ranges the fire control unit is offset from the elevating barrel mass.
This fire control system alone usually produces sufficient accuracy to ensure grenades land within the effective radius of their warheads, but the Striker/ CG40 goes one further. Bofors of Sweden has developed 40 x 53 mm PP-HEDP or PP-HE (PP -- Programmable Prefragmentation) grenades specifically for the Striker/CG40. These grenades incorporate a fuze that can be programmed by the fire control system to either function on impact or create a fragment-scattering airburst above the selected target area at ranges up to 2000 metres. The Swedish fuze is based around technology originally developed for programming 40 mm Trinity air defence gun projectiles, so programmed data can be induced into the grenade at the instant of firing. The grenade fuze even has a self-destruct function.
To expand the international aspect of the Striker/CG40, Nammo Raufoss of Norway is developing a pre-fragmented warhead surrounded by steel balls to increase on-target effectiveness. The Striker/CG40 AGL system has been ordered for US Special Forces as the 40 mm Mk 27.
Singapore Technologies Kinetics has also introduced electronics to AGLs, but whereas the Striker/CG40 involves a complete system, the Singapore approach is to provide an add-on kit that will enhance the performance of existing AGLs. The product is known as the 40 mm Air-Bursting Munitions System, or ABMS. Once again, a single fire control system unit incorporates a laser range finder and a ballistic computer that accurately calculates the correct target range and the necessary barrel super-elevation. However, with the ABMS the range/time data is introduced into the locally-developed grenade by a programming coil as the grenade leaves the muzzle. When the required range has been reached the time fuze functions to produce an air burst able to neutralise targets normally hidden behind frontal cover. The fuze induction system is based around the Swiss Oerlikon Contraves Pyrotec Ahead fuzing system, normally used with 30 or 35 mm air defence guns.
It has to be emphasised that the Singapore ABMS is an add-on upgrade kit that can be used on almost any existing 40 mm AGL. This includes the local 40AGL and lightweight SLWAGL (mentioned above), and the Mk 19.
Another potential upgrade for the Mk 19 is the Brashear LP Small Arms Fire Control System (SAFCS). This is virtually a miniature tank-type fire control system in a single unit with a performance stated to increase Mk 19 effectiveness by a factor of fifteen at 1000 metres, yet weighing only 4.1 kg.
The next AGL generation will doubtless be based around systems epitomised by the US Army's future Objective Crew Served Weapon (OCSW). Still under development, with General Dynamics Ordinance and Tactical Systems as prime contractor, the tripod-mounted OCSW fires what are effectively 25 mm air bursting high explosive grenades that function over a target area up to 2000 metres away. If required, the grenades can be programmed to detonate on impact.
The OCSW will combine a light weight (weapon, tripod mounting, fire control unit and 31 rounds will weigh approximately 23 kg, so a crew of two can backpack a combat-ready load) with an electronic fire control. The latter will eventually feature such capabilities as automatic target tracking and a night vision capability, while the grenade fuze utilises a spin-count principle to obtain optimum accuracy. Cyclic rate of fire for the OCSW will be about 260 rds/min and soft recoil will again be employed to reduce firing stresses and thus keep gun/launcher weight to a minimum.
It is intended that the OCSW will eventually replace US weapons such as the venerable 0.50/12.7 mm M2 heavy machine gun and the current Mk 19 AGLs. That is still some way off in the future for the OCSW development plan is that the current scheduled in-service date will be 2007, or even later if past experience is anything to go by. Whatever that date might be, the AGL is definitely here to stay.