Considering the high damage and decent explosion radius, it is tempting to use the 40mm HE Grenades on players. However, since they are so challenging to acquire, they are often put to better use as raiding tools.
The only way to get 40mm HE Grenades is to loot them from heavy scientists.
The massive benefit to using 40mm HE Grenades as raiding tools is the speed at which you can fire them and their explosion radius.
While they do less damage than rockets, they can be fired quickly towards a doorway that players actively protect during an online raid.
Players defending doorways and chokepoints are likely to be caught in the blast. The 40mm HE Grenade will hit for close to 90 damage, depending on their armor.
You will need 6 or 7 40mm HE Grenades to take out a Sheet Metal Door, depending on what other raiding tools you have bought with you.