It's not the lag it's the Aim Assist.
Between the Demo and the Final game they modified the aim assist by cranking it up ( my main beef with the final game ) and not only did they crank it up, they also Ruined the aim assist.
It shouldn't really be called Aim "assist" because it does NOT "assist" your aim in the way you expect.
Let me explain
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The perfect example is when you are shooting a guy who is running to the side, you are shooting him but your bullet aren't registering, its only when he stops sprinting when it becomes easier.
It's lag right? your shooting where he was rather than where he actually is right?... wrong.
It's the aim assistance, the connection is fine so as long as you have 2 - 3 bars.
Ever wondered why sniping svcks so much balls?
It's because the game lags right?.. no. It's because of the aim "assist".
What the aim assist does is that when you are shooting at a moving target ( Not moving directly towards or away from you but side to side ). The aim assist actually pulls your aim slightly behind your enemy, not on your enemy.
Try it, try using the gauss, or the DSG-1 with aim assist, then try it without. I noticed an incredible difference and I was even Quickscoping successfully with the gauss, at close range, against assault rifle guys O_O.
If this is the case (which it is ), then the aim assist is surely something that can be fixed ( Although I doubt it will now that C2 is virtually dead online ) all they have to do is put it back to the demo's aim assist and C2 will be alot less annoying
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Trust me, i'm know i'm right on this one.
Go try it out for yourselves, This applys to all weapons, yes it will require abit more focus to aim but you will notice that the connection is fine its just the **** up aim assist.