I think that the most practical approach to produce a rifle/ hand grenade is not to adapt a hand grenade to rifle-launch but to adapt a rifle grenade design to hand-throwing. A weapon like the FN Herstal Bullet-Thru® Telgren is similar in size to a hand grenade in its untelescoped state (40 x 190mm). All that is really needed is a pin, safety lever and new fusing mechanism. Since the fuse will need to be changed a multi-option model can be fitted, as will be described later.
I feel a good basis for the rifle/ hand grenade would be FN Herstal Bullet-Thru® rifle grenade, which used to be called the Telgren. This has a pull-out tail section that contains the firing pin. When in the travelling configuration with the tail retracted, the firing pin is not in line with the detonator in the grenade head. To fire the grenade the tail section must be pulled out and the grenade placed over the rifle muzzle. The grenade is a bullet-through design so there is no need to load a blank/ grenade-launching cartridge since it can be launched by ball, AP or tracer rounds. When fired a spring retracts the tail of the grenade back into the body but also rotates it so the firing pin is brought into alignment with the detonator. Arming distance is between 5 and 10m. Launch velocity is 85m/s with a 7.62x51mm weapon, 65m/s with a 5.56x45mm. Range is 400m with a 7.62x51mm and 300m with 5.56mm. Each grenade weighs 320gm (11¼oz). Recoil for a 5.56mm is < 45J and < 60J for 7.62mm.
A rifle/ hand grenade would be very similar but have an electronic fuse and a separate firing system for hand-throwing. Electronic grenade fusing systems have been in use for some time, one of the best know companies using these being the British company HALLEY & WELLER.
This hand-throwing fuse system would operate by the familiar safety-lever and pin system, although the lever will be a non-ejecting trigger bar rather than a fly-off lever. This trigger bar or the tail might also mount a folding ladder sight that can be used when the grenade is muzzle-launched. The hand-throwing system will only work when the tail is contracted into the grenade head.
When the tail is pulled out for rifle-launch the hand-throwing fuse will be physically separated from the detonation circuit in the grenade head. If the safety pin is pulled while the tail is extended there will be no effect other than the safety bar partially releasing. The grenade will arm when rifle-fired regardless of whether the safety pin is in place or not.
If the grenade was readied for rifle-firing but was not used, the tail can be collapsed back into the head to return it to hand-throwing/ travelling configuration. If the pin was pulled while the tail was out then retracting the tail will not reactivate the hand-throwing fuse system. To rearm the hand-throwing system the safety lever must be fully depressed and a safety pin reinserted. Alternately, if the safety lever has been released it will physically block the tail being fully contracted back into the grenade body. The ignition system for hand-throwing will only work if it is in contact with the detonation circuit in the head, which only occurs if the tail is fully contracted. The tail cannot be fully contracted unless the safety lever is pinned down.
On the right is a crude representation of what a rifle/ hand grenade might look like:
An electronic grenade fuse is not only more reliable and consistent, it can also have several fusing options. These may include:
For ease of use these options can be selected using just two tumbler or slider-type controls: one to select or switch off the Impact mode, the other to set the Time/ Self Destruct delay option. The Impact dial would have the options Impact, Impact + ½ and Off. The time dial has options such as 4 sec, 7 sec and Instant (0). Booby trap setting would be the controls set to Off, 0, easily remembered due to the two Os in booby.
As well as the general-purpose fragmentation rifle/ hand grenade there are likely to be several other types. A smoke/ incendiary rifle/ hand grenade containing white or red phosphorous would be very useful. There may also be requirements for a non-incendiary screening-smoke grenade containing something like HC or TA composition.
Another potentially useful rifle/ hand grenade would be a flash-bang/ stun grenade that can be either hand-thrown or rifle-projected. In the latter mode it would be useful in deterring mobs.
Another consideration is that the rifle/ hand grenade should also be compatible with 7.62x51mm and 6.6mm rifles and 9mm and .45 submachine guns.
A practice version of the grenade in rifle-launched configuration should be built that can be launched by blank rounds but has the same trajectory as the live grenade propelled by a ball-round. Training could be an up-dated version of the medieval game of Rover: essentially golf using a longbow. The soldier would move over a course of rural and urban terrain with targets at varying ranges and elevations, and be required to hit each with a practice grenade.
The variant above is inspired by the MN30 rifle-launching attachment of the V40 mini-grenade (Holland). Unlike my previous design this is non-telescoping and has a total length of about 7" (185mm) and calibre of 40mm. Weight will be about 300-400gm so can probably be hand-thrown 35-40m. Effects will be similar to an M67.
The safety lever is on the tail, allowing it to be thrown like a compact stick grenade. In rifle-mode the barrel of the rifle passes through a hole in the safety lever, preventing the lever from operating even if the pin is removed. The non-ejecting lever can also be used as a pressure-release trigger for booby trap applications.
Stabilization is by weight distribution and a compact cogwheel type tail, copied from the MN30.
The sides of the head are fitted with 3 wire petals that form a self-righting mechanism to place the grenade in a vertical position just before detonation and send the cylindrical pattern of fragments in a roughly level orientation. The petals deploy just after impact and before detonation or just before timed detonation. A simpler design would omit this feature.
Rifle/ hand grenades would also be used in the High Angle Grenade Launcher and could be adapted for launching from Recoilless Grenade Launchers or 3BT Grenade launcher. For launch from the MBIL/ RLGL the grenade is fitted with a rocket that has a post that inserts into the grenade’s extended tail. For the 3BT the grenade is attached by a sear pin to a post on a cartridge case. Once sufficient chamber pressure is reached the pin breaks and the grenade is launched.
The family of rifle/ hand grenades might be complimented by the Quarter-Kilo hand grenades and certain designs of rifle-launch-only grenades. These might include a Paraflare illumination grenade and a HEAT-frag grenade for use against light vehicles and personnel.
An alternative to the latter might be a EFP (Explosively Formed Penetrator) grenade. This technology has begun to be offered for RPG-7 rounds. The rocket warhead detonates about 30m after launch and creates a slug of metal moving at around 2,800m/s. Due to its short time of flight the projectile has a very high hit probability and is not effected by countermeasures such as RPG-cages/ slat armour. EFP offers the infantryman considerable capability against helicopters. This technology has been used for some artillery-delivered sub-munitions but to the best of my knowledge hasn’t been tried with rifle-grenades. One Russian EFP round for the RPG-7 has a detachable, segmented splitter ring assembly. If the round is fired with this in place the slug of metal is shattered into a shower of fragments for anti-personnel use. In effect this converts the round into a Flying Claymore.
Alongside the designs suggested above a number of large-caliber rifle-grenades similar to the Energa and Norinco Type-67 should be made available. These grenades typically are 70mm to 75mm in calibre and weigh between 1½ and 1¾ lbs. Fired by a rifle round, they have a launch velocity of 42-75m/s, a direct-fire-range of up to 75-100m and a high-trajectory range exceeding 250m. Penetration for the South African copy of the Energa is given as 375mm of RHA, nearly 15". The Rhodesians often issued Energa grenades to the point man of a patrol, giving him RPG-level firepower during an encounter without the problems of back-blast and the added weight of a launcher.
Such grenades have obvious applications for anti-tank ambushes in urban terrain where engagement range is often less than 100m. Destructive capability is similar to an M72 but the grenades are lighter and can be launched without back-blast or from confined spaces.
Many of the more recent designs incorporate some from of rocket assistance or booster charge to increase range. An interesting possibility is to instead use such technology to reduce the time of flight of the round during short-range engagements and therefore increase the chances of a hit. Being able to launch the round with a standard ball round rather than a grenade-launching cartridge would be desirable and it is possible that an EFP warhead could be used.
These rifle-grenade ideas should be combined with the DGLconcept to creat under-barrel or stand-alone launchers.
Another form of rifle-grenade that should see wider use is the Israeli IMI ARG/ AP-50. This is a form of rifle-grenade that does not leave the muzzle but instead projects a cloud of flechettes. These have proved very useful for firing through chain-link fences erected to protect a position from RPGs. The 53mm calibre round weighs 640gms and fires 160 flechettes in a 10° arc with a range of 50m. Such a weapon would be useful for any situation where the enemy was likely to be encountered at close range. Carlton Meyer coined the phrase Rifle-Claymore for a weapon of this type.
Other ideas about grenades can be found on these pages:
By the Author of the Scrapboard :
Attack, Avoid, Survive: Essential Principles of Self Defence
Available in Handy A5 and US Trade Formats.