Scout Rifles are used primarily by Infiltrators taking objectives, hacking, scouting, or frequently finding themselves in head-to-head combat.
The VS rifles are unaffected by the reticle sway and bullet drop (even if you use a suppressor) of the sniper rifle class. All others have normal bullet drop.
Each empire has 2 types of Scout Rifles:
a lower-recoil, slightly faster-firing semi-auto with the same mag-size as its Sniper Rifle counterpart (albeit with less damage at range) and,
an extremely accurate, blisteringly fast, fully automatic rifle with a debilitatingly small 20 round mag.
The primary trade-offs between the two types are:
Damage per second in a close-to-mid range fire fight, a match easily won by the full auto variants.
Effectiveness at mid-to-long range, where the full-auto rifles greatly suffer from their small clip size and reliance on rapid headshots (made increasingly more difficult at longer ranges).
The full-auto scout rifles are best used within 15-50 metres, with a focus on headshots due to their extremely reliable full-auto accuracy; with this, you can out-damage even the dreaded "heavy assault with their shields up", by focusing fire into the neck and head. If they were to try to do the same, they would have a much lower percent of hits (hopefully due to their aim jumping from being shot in the face, or from the naturally higher recoil of their LMGs) and lose the DPS battle by a decent margin. Alternatively, if both shooters are firing for the body, the LMG's higher damage and the HA's higher health pool will make short work of the cornered infiltrator. Avoid moving into extremely close ranges where hip-fire can reliably hit the head, as the fully-automatic Scout Rifle loses all advantage.
Note: The maximum effective range of this weapon is very synergetic with theIRNV Scope
The semi-auto Scout Rifle should be compared to it's Sniper Rifle counterpart, where it maintains the same class advantages as the fully-automatic Scout Rifle: low recoil, no sway.
While the sniper variant has the same clip size, more damage and faster projectile speed, the scout-class advantages weigh heavily in the semi-auto Scout Rifle's favor as the engagement gets closer. There comes a tipping point where losing damage and projectile speed is minor compared to the accuracy gained by not dealing with sway or bullet drop, and the extra damage boasted by the sniper variant may not have mattered anyway, as they both kill in 1 headshot, with a quick follow up to the body (Though the Scout Rifle loses this ability at longer ranges, especially with a suppressor attached).