Values listed in brackets are for alternate (secondary) fire.
The bullpup is the commando's basic weapon; an assault rifle with low-medium damage, a good rate of fire, and low cost. With the relevant bonuses it can be useful and viable primary weapon even on the highest difficulty, although its low cost allows it to be used as a backup weapon while a more powerful one can be used instead.
As with almost any weapon, try to aim for the head. The relatively low recoil means you should be able to get many consecutive head shots with little difficulty, killing many of the weaker specimens very quickly.