They are viable in the correct situations. You definitely don't want to use them in long range, that's why you got Rifles. You don't want to use them against armored targets, as against those, if it is not a headshot, the bullets will simply bounce off their armor, they'll get stunned a bit as well. I use them in CQB against any target, but the key is, going for the hit stun (By shooting them anywhere) then going for the headshot, otherwise they are not good. They get more useful in the Desert Siege and Island Thunder, where not everyone is wearing armor. Just like every weapon, it is a matter of using them in the right scenario.