System Reference Document

BURST FIRE 

Automatics and other weapons capable of Burst Fire can fire three round bursts. Three round bursts use up three rounds of ammunition (duh) and are made at a -1 Penalty to the Attack, due to recoil. The character firing the burst must choose whether to "hose" or "spray" before making the Attack Roll

Hose: Attack deals +2d6 damage

Spray: Defender receives a -3 DM for this Attack.