Burst Fire is a mod for 40mm Cannon that appears in Titanfall. It modifies a weapon to fire in a three-round burst, rather than semi-auto. This mod significantly lowers the damage and accuracy of individual shots, and increases ammo capacity to 21.
This mod is especially useful in downing pilots and minions, as it still does high damage to them with both direct hits and blast damage. It also makes it easier to hit enemy titans as well. The major drawback to this is the lowered damage, which is almost half the original. It takes much more lead to down enemy titans and dropships.
Titanfall 2 Edit
This modification does appear in Titanfall 2, now renamed Burst Loader. It is only available for Tone and instead of making every trigger pull a burst, the cannon must now be "charged" by holding the trigger, allowing for one, two or three shots to be fired. It is generally eschewed in favour of other kits mainly due to the reduction in base fire rate; Pulse Echo, Rocket Barrage and Enhance Particle Wall being the most common.The main reason for this is that the bonus is both negligible and means that aiming automatically turns the first shot you fire into a burst.