In SR4A pg 154 your full auto had the option of narrow and wide Bursts with Narrow (basically focus fire)giving you up to +9DV while the wide version (spreading your fire to increase chance to hit hit) gave up to a -9 Dice toward the target's Defence against it.
In SR5 pg 190 there is no equivalent of Narrow burst for Full Auto, rather all bursts are what was called Wide in 4th, applying a penalty to defence.
However, in Run & Gun pg 110 they do offer the Optional Rule RG6:
QUOTE (RC6 Run & Gun pg 110)
DAMAGE FOR NO DEFENSE
If an attack decreases a target’s Defense Test pool below 0 dice, additional penalties are added to the DV of the attack at a rate of 1 DV per two lost dice.
This makes Full Auto or Burst Fire attacks against unaware or restrained foes truly deadly.
edit:Of course if someone knows they are facing full auto they may sacrifice some initiative and go with the full defense option to try and add Willpower (or other stats depending on special qualities) to their defense.
I believe this fits what you were looking for?