1. 40mm grenades are not accurate
In fact, the 40mm grenade is intrinsically very accurate. Under technical test conditions it can give very small groups. However, several factors make it difficult to hit a target in real-life conditions:
- Most grenade launchers have very basic sighting systems, making accurate aiming difficult.
- The high, curved trajectory of the grenade means that precise range estimation is essential. If you aim accurately with the 150m sight position and the target is at 175m, you will miss.
- Firing on an uphill or downhill slope requires aim to be adjusted.
- Different types of grenades (Training, HE, HEDP…) have differing trajectories. A sight that is good for one type may not be good for the others.
Calculating and adjusting for all these variables is virtually impossible.
When developing the FN® FCU Fire Control Unit, which measures range and slope angle, makes all the calculations and automatically adjusts the aiming point, it was clear that the 40mm grenade can be extremely accurate if aimed correctly.
2. The 40mm grenade is not reliable
In the past 40mm grenades could have a high percentage of failures. This problem has been greatly reduced by improved fuse technology. Grenades supplied by a good quality manufacturer are very reliable. To ensure almost 100% reliability, even if impact detonation is affected by soft snow, bushes, etc., the grenade can have a secondary self-destruct time-delay fuse that will detonate it even if the impact fuse fails to function.
3. Grenades are dangerous for the user if fired at close range
Explosive grenades have fuses with a minimum arming distance. When launched, the fuse will arm itself during the first meters of travel. If the grenade hits an object before arming is complete, it will not detonate. The arming distance varies between grenades and manufacturers, but is generally about 15 meters.
4. The 40mm grenade launcher gives very heavy recoil
When fired from a launcher attached to a rifle, the recoil of the 40mm LV grenade is relatively light. The weight of the rifle + ammunition + launcher absorbs most of the recoil.
The recoil force is higher when fired from a lightweight standalone launcher, it is similar to firing a 12 gauge shotgun.
5. All 40mm grenades are the same
As with other calibres such as 9mm, there are several different 40mm calibres.
The 40x46mm Low velocity (40mm LV) grenade is fired by the great majority of standalone or underslung hand-held launchers.
The 40x53mm High Velocity (40mm HV) grenade is the calibre fired by Automatic Grenade Launchers. These are heavy weapons fired from a tripod or other mountings. The 40mm HV generates too much recoil to be fired from a hand-held launcher.
There are also 40mm Medium Velocity grenades. This category is not yet clearly specified, but comprises grenades similar to the 40mm LV with a higher velocity. They are generally made to be fired from 40mm LV launchers. However, care must be taken before using these grenades as they generate higher recoil force. This is not only less pleasant for the shooter, it can damage the launcher or the rifle it is fitted to. The FN SCAR® and its launcher were specifically designed to withstand current 40mm MV grenades.
Modern launchers and sighting systems such as the FN® FCU Mk3 allow the 40mm LV grenade to achieve its full potential, providing invaluable complementary capability for infantry units.