The Underbarrel Shotgun is a rail attachment that can be certed for some select-fire weapons. It can fire a single shot before having to reload, and can have up to 4 rounds (1 in the chamber, 3 in reserve). This cannot be expanded using the Ammunition Belt or Grenade Bandolier. The Underbarrel Shotgun can kill any enemy (except for MAXes and Heavy Assaults with their shields raised) in one hit at close range. This puts it on the same level of effectiveness as a pump-action shotgun. It works quite well with the Light Assault class.