There are a select few weapons that majorly outshine all the others in the game. The most overpowered, but not extremely common is the Type 95. Why is it overpowered? Two hit kill potential all the way up to mid range, extraordinary fire rate, and only borderline "moderate" recoil. ACR is OP because of it's pretty standard damage, along with almost impeccable accuracy, moderate fire rate, fairly large range, and has high flinch, meanining you will win 9 out of 10 gunfights. The ACR has litterally NO downfall. The MP7 is definitly OP.  Litterally NO recoil whatsoever, pretty decent fire rate, extraordinary range, high 3 hit kill potential, the list goes on. And the worst part is, IW is too focused on buffing guns to make them as powerful as these three (and they failed epically), instead of bringing these OP weapons down a notch.