Burst Fire

Here’s the Official ruling from the Game Designer:

Any form of burst or suppression fire takes one round.

In terms of the number of bullets/bolts required for a burst, for spread burst, you need a minimum of three bullets/bolts per target. For aimed burst, use the same unless the weapon is something like a revolver or some such where “burst fire” is actually representing a “double tap”. Likewise for fully automatic weapons like machine guns, bursts may trivially go through tens of bullets.

The rules allow for finetuning, so GMs with a plethora of gun expertise can adjust the rate of ammunition to suit specific weapons. The weapons in the HARP SF core rules are deliberately generic. I fully expect that we will have a lot more detail in a future sourcebook or combat supplement.