M310 smooth-bore high-velocity cannon

From Halopedia, the Halo wiki

Template:Ratings The 120mm High-Velocity Gun is an anti-tank weapon firing High-Explosive Anti-Tank shells at extremely high velocity, the kinetic force adding to the explosive firepower of the shell[1]. It is the main armament of the Grizzly main battle tank, which carries two of these weapons.[2] It is more powerful than the standard 90mm High Velocity Cannon equipped on the standard Scorpion tank.

References

Template:UNSC Heavy Weapons