In my opinion, there's really no OP guns in this game. It feels much more balanced than previous titles. There are absolutely best opportunities to use specific weapons, but I have no problem with people playing with any gun. In fact, I'd rather see a larger amount of ARs like the AK-12 lying around after I kill a few people, gives me a better option of secondary to pick up when needed.
I feel instituting "nerfs" to weapons pushes people away from that weapon, just by the fact there was announcement to say they are adjusting it. A lot of the time they are not huge changes, but it definitely affects the numbers using the weapon, even if the adjustment is minor.