HE rifle grenades have an impact fuse. Their generic damage profile is 6d20 EXP-DMG | 1 PEN | M. EXP.
Grenades specifically built for being fired out of the end of a rifle began to appear during WW1 and remain the infantry squad's primary explosive weapon in many armies around the world, notably with the French. HE grenades are meant to be used as anti-personnel munitions.