Correct me if I'm wrong, but we are talking ACR and Gauss when talking the 4 round bursts, right? Most of the SMGs/LMGs have higher ROF if I recall correctly. Auto Rifle you may have a point, at the least higher ammo consumption or a requirement of a burst per target engaged.
Nope, SMG, Autorifles, ACR's and Assault Rifles all fire 4 rd bursts. Gauss Rifles fire 4 or 10 rds. LMG, MMG, HMG (from JTAS) all fire multiple 10rd bursts, and VRF GG fires an entire ammo dump worth in a burst.