not being able to deal big damage with one shot, no good piercing. I would buff its damage. Maybe make it pierce shields. Cmon compared to grudge raker or drake guns - rifle is pathetic.
Also Kruber’s rifle.
To be honest weapon balance is all over the place right now.
Yeah especially around sienna (beam staff) 
Everything feels weak in comparison, but rifles for Kruber/Bardin especially.
I don’t know, I’m pretty sure it’s meant to take care of specials in a pinch. And it does a great job of that with its range. Drakefire pistols can be a bit unreliable at range.
I believe it takes 5 headshots to kill a chaos warrior. Still I think the biggest problem with the rifle is its accuracy, the weapon spread seems to be to outside of the crosshairs instead of the inside:
http://forums.fatsharkgames.com/t/issues-with-misrepresented-weapon-accuracy/20229?u=3-leaf-clover
I noticed the accuracy problem too with the handgun. its good at killing specials when it hits them, but it just doesn’t reliably hit what I’m aiming at so I stopped using it.