The multiplas rifle is a plasma-based weapon. It is most easily distinguished by its three plasma barrels at the rifle's tip, which fires three very destructive rounds of plasma. It uses one round per projectile, for a total ammunition consumption of three rounds per trigger press. Like most plasma-based weapons, the multiplas rifle causes a large green burst of plasma upon firing which partially obstructs the view. In addition, the plasma bolts travel at a slow rate, resulting in the need to lead the shot.
Due to the fact that it fires three plasma bolts at once, it can score a Critical Hit for each shot outside of V.A.T.S. This attribute allows it to sometimes hit a target for a huge amount of damage per shot.
The multiplas rifle can fire a total of about 245 times using standard cells, the equivalent of 25 reloads, from full condition before breaking.
Plasma rifle - The common variant found in Fallout: New Vegas.
The multiplas rifle is the plasma equivalent of the tri-beam laser rifle, as it fires three bolts of plasma per shot.
If the bomber is allowed in during the Birds of a Feather quest, the rifle will be part of the ordinance that gets destroyed.
If used to attack the ants in the quest Ant Misbehavin', it will cause them to explode.
In the Fallout: New Vegas Official Game Guide, there is a piece of concept art for a triple-barreled mutliplas rifle. The barrels are yellow-tinted, there are extra wires running along the side and cell basket, and there is also a different grip than the one seen in the game.