I don't understand why every time in this game,enemies kill me in really few shots...and I have to shoot one or two mag to kill someone.

Maybe it's the lag effect?

Or first weapons are too weak?

I've heard about lots of people using a particular sniper,maybe that's the point...but it should be used by a really lot of people if this is the problem...

Please help,I'm on a x360 and a good player in every shooter game (halo,cod,gow,tf2 and so on)

Could be the lag, but it really does depend on the gun. For example: the AR's do much more damage than the SMG's. The SMG's also vary in damage from 25-35 (thereabouts)

Just gotta keep trying.

try the vector-look-a-like or carbin up close

Probably is lag. But, weapon does matter. I use the Gerund. Tears people apart. But you need a different strategy than in COD. Moving more and flanking and such is how you win. Not always just seeing them first. Slide also does good to get behind cover. You need to run, jump, and slide while shooting to be able to survive. Use buffs and don't leave your teammates. All I can say.