Idea is that 40mm grenades are fired at anything suspected of being a command detonated mine or booby trap, detonating it before the vehicle needs to get within a few hundred metres. At the moment (Feb 2005) I have found no information if this has been tried operationally. The 40mm Thermobaric round may prove to be particularly effective for this purpose. Having a M79 on each vehicle has other advantages since it can be used to fire LLW rounds in the event of a civil disturbance.
Another auxiliary weapon which quickly became indispensable was the M79 and its variants. Each tank carried one, and when stuck out in the hills alone, we used to fire close-in H&I with the Bloop Tube. They were good for Recon-by-Fire too, and more than one RPG artist got sent to the promised land by a 40mm. There's also a tear gas round for the weapon. It's useful in LIC, as it's non-lethal. After all, the object is to separate the sheep from the wolves, not de-populate the area.
"As an infantry platoon leader [in Vietnam] I initially carried a rifle, just as the book suggested. Part way through my tour, I was struck by the idea of carrying an M79 and a pistol instead. [The M79 was light enough that] I could carry it in one hand, with the other hand free to operate the radio -- an important duty while in contact. A shot round in the chamber could provide a quick burst of self-protection if needed, and I wouldn't even have to change my grip or take careful aim. Another advantage was that I could use smoke rounds to mark enemy positions for armed helicopters instead of smoke grenades to mark my own position. I could also use smoke or high-explosive rounds to mark targets for my machineguns. I quickly scrounged an M79 and carried it for the rest of my tour."
BG John Scales, Spring 2002 issue of INFANTRY.
The M79's capability to fire Illumination rounds was doubtless also useful to a platoon commander, allowing him to simultaneously illuminate a target and signal his platoon to open fire.
"I guess the thing that sticks in my mind most about the M-79 is it was great to have along when it hit the fan and always the gunner needs to carry it with the breach open. If the weapon is going to be redeployed I hope this one little bit of safety advice goes with it. It will save lives if breach open SOP goes with the weapon."
In some units the M203 should be replaced by a repeating grenade launcher. The South Africans use a revolver based model that has the merits of being both simple and combat proven. Such a design could easily incorporate a gas powered ejector mechanism. The chamber that this empties can be used to keep the weapon topped up without opening the cylinder. The weapon could also be loaded with two or three round clips.
A revolver grenade launcher fitted with a Fuse setter interface may have a performance similar to the OICW. Such a weapon might later be modified to fire 20mm OICW rounds and this route may prove a simpler alternative to the self-loading OICW.
For close combat a repeating grenade launcher loaded with canister could prove very useful.
In other situations the same weapon can be loaded with Baton and Gas rounds.
The 40x46mm grenade has only a small casualty radius so must be delivered close to the target to be effective. Since the grenade has a low velocity and very curved trajectory this can often be difficult. A multishot weapon allows rounds to be "walked" onto the target. An accurate means of estimating the range to the target also increases the effectivness of low velocity grenade launchers. An interesting sighting system has been introduced for the grenade launcher for the FN F-2000 rifle. A rangefinder lases the target and an LED lights up when the weapon is raised to the correct angle for firing. A similar system could see broader applications, including for long range machine gun fire.
In principle systems like the FN Grenade Launcher are simple to operate. Lase the target and then raise the muzzle till a light comes on/changes. Basically a simple clinometer. A system worth having but only useful if you have enough time to lase the target and it isn't moving much. The scope used on the M32 seems an improvement over the M203, but it is essentially still a quadrant sight so needs to be set before firing. Often GLs will be used for snap shots when there is not time to adjust sights or lase targets. In the past that has meant the use of a ladder (leaf) sight but they can only be used if already erected, and if in position can easily get snagged on undergrowth etc. That is why the Eotech sight(left) looks so promising. I'd be inclined to combine this with a spirit level type device as used on many commando mortars. This would act as a backup and sight for high angle fire. You just point the weapon and raise or lower the muzzle till the level of the coloured liquid matches the intended range. Sometimes the grenadier is going to need to guess the range, but something like the golfer's LRF will be useful for creating range cards and help the grenadier learn to hone his skill at judging distances. True, they are not mil-spec, but on the other hand they only cost a couple of hundred dollars and weigh under 8oz.
There are still applications where the M203 is a more appropriate weapon:- One example is for a close quarter battle assault team. While the ability to put a grenade through a window at 125m is useful, a lot of combat will take place within the minimum range of the grenade gun. In such situations the weight of a multi-shot launcher might not be justified. The M203 weighs less and allows the grenadier keep his rifle or SMG ready for firing. So too would a three shot grenade launcher Another application is for a scout or FAC team that mainly uses its grenade gun for marking targets, although the 3BT (see below) is a better choice for this.
Disposable Grenade Launchers (DGL) are a family of one shot disposable grenade launchers designed to fit to the Picantinny rail interface system of a rifle or SMG.
They can also be hand fired, mounted in batteries or utilised in booby traps.
Disposable Launchers fill the same role as rifle grenades- they give each man in the squad grenade projecting ability and are a supplement to the 40mm grenade gun, not a replacement. They offer several advantages over grenade guns and rifle grenades:-
Unlike rifle grenades they can be carried "ready to fire" and still allow the rifle to be used.
When the launcher is not fitted the rifle is unencumbered and more responsive.
Tubes can be built that fire 40x46mm cartridges, conventional and rocket assisted rifle grenades or hand-grenades. The charges used to propel the latter can be optimised for the projectile rather than just being a blank or ball round.
They can use captive piston systems for low-noise flashless launch.
DGL can use fire rounds that cannot be launched from grenade guns. Examples of these include-
Ring airfoil grenades- for flat trajectory shooting of either riot control or explosive.
Multiple loadings -for example, an anti-ambush round consisting of a canister rounds and a Ring airfoil White Phosphorus grenade. Multiple loadings of M203 rounds are also possible.
DGLs loaded with OICW rounds may be possible, but unless the rifle is fitted with a Fuse Setting Interfacer these will only function as impact fused projectiles. A simple interface unit where the detonation range is manually selected could be fitted to a rifle or made part of the disposable unit. It has been suggested to me that fired launchers should auto-eject from the rifle - this would be a good feature so long as this mechanism doesn't operate when the launchers are being fired handheld. I've called these devices disposable -should be cheap enough to be treated as disposable but for training purposes they may be capable of being reloaded several times.
A friend suggests an alternate strategy:- "These are a good enough idea that I suggest a small additional wrinkle: make two models. M1 is a robust steel and alloy version that can be reloaded by the soldier. This is for economical training purposes. M2 is a cheap plastic and fiberglass version, ideally w/ a break-apart feature that prevents it from ever being fired more than once. This is for advanced training and, esp., for war. If they're disabled by firing, no enemy can scavenge and reuse them, the way Charlie did much too well w/ discarded US ordnance in Nam. Why a training version? Because men must practice w/ these weapons a lot"
This is intended to combine the punch of a rifle grenade with the accuracy of a grenade gun. I thought such a weapon might be useful in open terrain or against fast moving light vehicles. It may replace the light mortar on terrain that is too soft for such weapons. The round I imagined originally resembled a modified rifle grenade mounted on a grenade gun case. Rocket assisted models would be possible. The launcher is a single shot break open weapon with a straight-line layout, and an optic sight mounted halfway down the barrel. This arrangement allows the greatest flexibility over the form of rounds that can be chambered. Because the recoil would be greater than an M203, the furniture would be separated from the barrel by a recoil buffer and another buffer built into the butt.
Since I first thought of this idea I've added a few refinements:-
The second is that such a launcher could also fire the same rounds as the MK-19 GMG.
The user therefore has a choice of hard hitting, flat flying or long-range projectiles. I'd originally imagined the weapon as being of a greater calibre than an M203, though the use of Mk-19 rounds would necessitate a 40mm weapon. This should not be a problem since 40mm RAGs were used by helicopter gunships in Vietnam and many rifle grenades are of around 40mm. The same weapon may also be able to handle M203 rounds. It is also possible that this weapon could be fitted with a discharger cup to fire larger projectiles. By fitting a discharger cup and providing a 40x53mm Ballistite round the HVGL could be used to project hand-grenades. Such a capability is most likely to be used in riot control applications for projecting tear-gas grenades. The German Granatbüchse 39, an anti-tank rifle modified to serve as a grenade launcher was often used with wooden bulleted rounds instead of "blank" ballistite cartridges. The TP 40mm round could be used in the same way.
The 3BT has two important advantages over other grenade launchers. The first is that its break-open action allows it to accommodate very long rounds. The second is that its recoil-reducing systems allow such heavier rounds to be fired with greater comfort. The increased kick is converted into a more gradual push.
For a projectile to be stabilised by rifling it must usually have a length to calibre ration of 7:1 or less. This is why arrows and long-rod penetrators use other systems such as fins. For a 40mm weapon this means we can fire a stabilised projectile of up to 11" length. This gives us a theoretical capacity of 77 cubic inches or 1.4 litres if the round was a true cylinder. This suggested that the 3BT can be used to project high capacity smoke or riot gas rounds. Since the sectional density will be higher than larger capacity rounds of similar weight, the round can be expected to travel to a greater range and with a flatter trajectory. Such capability will have both police and military applications.
The main HEAT round of the 3BT will resemble a finned rifle-grenade mated to a 40mm grenade gun case (although the case may be lengthened). There is good precedent for this; the first weapon to use the High and Low pressure principle was the German PAW 600, which used a modified 81mm mortar round attached to a modified leFH18 howitzer casing. By using fin-stabilisation in conjunction with a slipping ring system the HEAT round fired from a 3BT does not need to be spin stabilised. Therefore not only does the round carry more explosive than a M433 or M430 40mm HEDP grenade, but it uses it more efficiently. The 3BT loaded with such a round will be a useful anti-vehicle weapon, particularly when fired from confined spaces such as is likely to occur during urban combat.
Another useful capability offered by the 3BT is that it could be used to fire over-calibre muzzle-loaded projectiles. This has potential applications in the anti-vehicle role or for the delivery of chemical or conventional and thermobaric explosive loads. Over-calibre grenades would either have a spigot tail that fits over the muzzle or a tail that fits down the barrel. The latter will probably require the use of a ballistite round, while the former could possibly be a form of bullet trap. This may actually be feasible with a 40mm grenade since the fuse does not arm until 18 to 30m from the muzzle. For an idea of the form of such a grenade we can look at the various designs of large caliber rifle grenade such as the Energa and Norinco Type-67. These are 70mm to 75mm in caliber and weigh between 1 ½ and 1 ¾ lbs. Fired by a rifle round they have a launch velocity of 42-62m/s, a direct fire range of up to 75m and a high trajectory range exceeding 250m. A skilled operator can probably drop a grenade onto the thinner top armour of a vehicle. Penetration for the South African copy of the Energa is given as 375mm of RHA, nearly 15". The Rhodesians often issued these to the point man of a patrol, giving him RPG level firepower during an encounter without the back-blast and added weight of a launcher. They also issued two types of ballistite cartridge, the weaker being used for close range hip or underarm firing. Fired from a weapon such as the 3BT we can expect the range and velocity of similar sized projectiles to be much greater. This will make the 3BT a very useful weapon for anti-armour ambushes where the firer can operate from confined positions such as buildings or spider-holes.
Overcalibre grenades fired by the 3BT could be designed with tails that fit inside rather than over the outside of the barrel, allowing the projectile to be spin-stabilized by the rifling. An overcalibre round of similar performance and form to the 140mm Brunswick RAW is a possibility.
The 3BT could also be used to fire multiple grenade rounds. This might include a revival of the M397 bounding Airburst grenade. The larger capacity of the projectile would allow the use of more effective fusing systems such as proximity fuses that detonate the round before it reaches the ground.
There are many other possible roles for the 3BT. I see it as a very useful system for Low Aggression Military Operations. It can be used as a precision system to neutralize snipers, or can be used to fire a large capacity smoke round for defensive concealment. With Baton or Sponge rounds it can be used for long range Less-lethal force application. I can see a 3BT and a couple of dozen assorted rounds being part of the standard equipment of all vehicles on Peacekeeping or other LAMO type service. The 3BT may also replace the platoon mortar in some situations. Its range and accuracy would make it the obvious choice for target marking teams.
The Philippino company of Floro International offers a "High Velocity Grenade Launcher". Essentially a rifle that fires 40x53mm grenades. It appears to be a single shot semi-automatic weapon that uses recoil forces to open the breech and eject the spent case, rather like the mechanism of the Russian PTRD-41 anti-tank rifle. According to Jane's Infantry Weapons 2004-5 there are two models. The M2 is intended for firing from a bipod and weighs 10kg, while the M1 is for tripod or vehicle mounting and weighs 16kg. The M3 tripod designed for the Browning HMG can be used. The canister round contains 200 balls of steel shot and has a range of 45m. This weapon is nearly what I envisioned for the 3BT. What is not apparent is if the breech clearance is sufficient to accommodate extra-length rounds. A version with a barrel that can be tipped up to load these should be possible.
40mm Mortar 40 x 53mm Grenades could be fired from a simple launcher of less than 4kg weight if only indirect fire was used. Such a weapon would be simpler than a 3BT and could be created from a re-chambered M79 with the butt reshaped to prevent shoulder firing. Such a weapon would be useful to Scout platoons, allowing them to illuminate or mark targets at ranges in excess of 700m. A double barrelled version of such a mortar would be possible. Batteries of such weapons would be useful anti-ambush devices for light vehicles.
AMR launched Rifle Grenades?
A option that has not been investigated with AMRs is their potential as grenade throwers. When the WW2 German PZB 38/39 anti-tank rifle became obsolete many were fitted with cup dischargers so they could launch grenades, including the various hollow charge models comming into service. To the best of my knowledge, spigot-tailed rifle grenades have not been built for AMRs, but the idea may have potential for both indirect and direct fire roles. Use of such grenades would give an AMR team an organic capability to illuminate distant targets during night actions.
Specialised Grenade Rounds.
Anti-windscreen round These are intended to be used in weapons such as the M203, the multi-shot grenade launcher and the Disposable Grenade Launcher. One option is a very soft HESH round -probably too soft to feed through an automatic action. This flattens against the windscreen and is fired by an inertia fuse. If this doesn't perform as expected then a warhead with three or more horns should be tried. This design has been used on crossbow quarrels and whaling harpoons for centuries. As one point hits the target it causes the round to flip over and turn perpendicular to the surface of windscreen. Fusing will be an inertia fuse with a short delay. Warhead is probably some form of shaped charge.
Adhesive smoke projectiles. These are intended to be fired from M203s, 3BTs or disposable grenade launchers to mark targets for air or artillery strikes. The shell shatters on impact and the contents stick to the target and produce a column of smoke. This allows a building to be marked high up where the signal is more visible and also allows mobile targets such as vehicles to be marked. Ideally this round should also be visible at night to both the naked eye and night vision systems. It is possible that this role could be performed by a grenade filled with some variant of napalm. In this case the round would also find other uses. From a World War Two American publication on tank-infantry co-operation:-
"Tracer fire proved unsatisfactory for designating targets to the tanks. The best method was the use of red or violet smoke grenades. The full-charge grenade produces too much smoke and obscures the target. However, if the fuze is unscrewed from the grenade and half the charge removed, an adequate amount of smoke will be produced." Rifle projection of the grenade is desirable for longer ranges. Best results are obtained by arming the grenade before firing as this will then give a trail of smoke to the target.