XM25 "good enough"

[Firn]

The UBGL is essentially an (almost) always ready-to-fire version of WW2-era rifle grenades that used muzzle cups (such as German Schissbecher).

Modern rifle grenades are descendants of those WW2-era rifle grenades that used a rather stokes-like principle (sitting on the muzzle).


The UBGL and stnad-alone GL designs add (just like the Schiessbecher) a certain fixed cost of mass. No matter how many grenades you carry, you gotta carry those 1-4 pounds of weapon.

Thus we have today the choice between
* rifle grenades with zero fixed costs (mass) thanks to ladder sights on the grenade itself
OR
* grenade launchers with fixed costs (mass), which in present GL designs is somewhat outweighed by less slow use (I wouldn't say 'quick' as long as you need to flip up sights or carry a carbine in ready position but have to switch to a stand-alone GL). The variable costs (mass per shot) is also smaller.

Recoil as a problem rather favours rifle-attached solutions, for the additional weight reduces felt recoil. A given warhead mass and a given trajectory (~muzzle velocity) will yield about the same recoil all else equal (weight and thus recoil differences between fin and spin stabilisation may occur, though).


In the end, today's rifle grenades have two niches:

(1) Whole small unit grenade salvo without many heavy GLs
(2) Large calibre grenades (see the Simon doorbreacher rifle grenade)

GLs have other advantages

(1) Potential exploitation of Medium-low pressure principle.
(2) Can be carried ready for fire in UBGL
(3) Can be a multi-shot weapon (revolver or pumpgun principle usually)
(4) already standardised
(5) No need for bullet trap or special ballistite blank cartridge
(6) Can be used on weapons of different calibres without aiming issues
(7) The limitation to few soldiers inherently leads to higher practice standard by specialisation in practice
(8) Propellant power is independent of rifle/carbine calibre and barrel length.

The French, Israelis and some other countries make still much use of rifle grenades.

I mostly agree with this summary.

It is interesting that early post-WWII AT rifle grenades shared the technology, warhead or even more parts with the missiles fired by rocket launchers. This goes for the French (AC58 - WASP 58), Swiss (Gewehrgranate 58 - Raketenrohr) and the USA (M31 HEAT - LAW72).

For direct fire the max. effective ranges seem to have been around 75 to 100 m. Used like spigot-mortar with rocket-boosted grenades ranges up to 550 m, although shorter ranges would have been the norm. Velocities of up to 75 m/s were achieved, but with 7,62 mm blanks and as said with a rocket boost. Not much compared to the claimed 250 m/s of the Wasp and still a lot slower than the 145 m/s of the LAW72.

The Swiss army used the training rifle grenade 58 to lay cable across obstacles, something which was already done in WWII.

All in all I could imagine those niche uses ( points taken partly by Fuchs) with modern assault rifles.

(1) Whole small unit grenade salvos (HEDP, etc)**
(2) Large calibre niche grenades (SIMON, smoke grenades)*
(3) Cable, Grapple, Cordex projector


All of them should be bullet-trap or -through types. If practical, the lighter rifle grenades (HE/HEDP) could also double as defensive handgrenades, like some German WWII ones.

*Heavy AT grenades don't seem to make sense enough compared to light rocket launchers like the LAW72 to develop, train and carry them.

**Light mortars have taken part of that role, even if the rifle grenades are of course a different kettle of fish.

P.S: I guess Schissbecher is a typo