The best option is it to duck behind cover and charge them when they stop firing. If you aren't hitting a target when you stop firing the Carb, there's a slight delay before you can fire again. Also, Flash Bangs or AR-C work well, because the Carby doesn't have hitmarkers, so even if they hit you they won't know it.
Seems like the only things that can kill are either explosive or a giant laser. Lame
When you get better with other weapons and learn their strengths and weaknesses, everything is relatively even, except SMAW (overpowered) or AEGIS (underpowered). Perks are more poorly balanced than weapons.