M-920 CAIN or Nuke Launcher

The effectiveness and efficiency of mass effect-based weapon technology has rendered large-scale deployment of highly explosive weaponry all but obsolete infantry weapons. UNSC scientists have prototyped a modified version of traditional high-explosive rounds that is applied to a 25 gram slug. When accelerated to 5 km/s, the round is devastating. Though a technically inaccurate label, this prototype weapon is nicknamed the "Nuke Launcher", and its high-explosive matrix generates an archetypal mushroom cloud on impact. It inflicts high damage with large area of effect. Very effective against armor, shields, and barriers.