Was probably either lag or you weren't really hitting them. I have noticed that if you don't shoot in short bursts or with sights up those guns are horribly inaccurate...especially if you just hold down the fire button on an automatic weapon...do agree though...the damage models are a bit off...i swear...shoot someone in the neck with a 50 cal and they walk away...I am sorry but their torso should have just about exploded from the impact....
Guess it goes both ways though, makes you that much harder to kill too :)
EDIT: BTW, I have the following: AMD64 4000+, 1GB 3200DDR, 40 Gb SerialATA, 256MB ATI Radeon X800 XT
And it still runs sluggish in spots...its a very demanding game.
