Well it makes them worse against MG's, because it's RA and not health damage that affects suppression taken afaik
Suppression is determined only by the weapon's suppression per bullet and its ROF. Basically it's just (ROF at range X * suppression per bullet). It needs to reach the threshold of 0.2, at which squad in the open becomes suppressed.
Additionally light and heavy cover give suppression resistance (I believe technically the amount of suppression required goes up). Only some abilities (Fire Up!) or bulletins (Volks -10% received suppression) can further influence suppression.
A squad's target size (/RA) does not matter, nor does the accuracy of the weapon.