The FN FAL HPFA is a heavy-duty assault rifle chambered in the 7.62mm cartridge. It is the only weapon in the game that empties its whole magazine (20 rounds) in a single burst. Such a fire rate, as well as the resultant ammo consumption, are unparalleled among the game's small guns.
Likewise unparalleled in the gun's size category is its average burst damage on soft and medium-armored targets -- some 280 and 150 Hit Points, respectively. The FN FAL HPFA is the only small gun in Fallout 2 that can exceed 1000 HP of damage in a good critical burst without the help of damage-boosting perks.
However, the weapon's comparatively low damage per round massively impairs its effectiveness against very heavy armor, unless critical hits are scored.