Anyways, I've noticed while playing De_Dust on 1.6 (NOTE: I have the CS:RU FE update which is a hi-def model pack) That the counter-terrorists are almost impossible to kill.
It's as if they have tactical shields all around them save for some (TINY!!!) spots. I mean, when you awp a bot 5 times 2 of which are on the head and end up getting knifed by the target bot, there is something wrong.
Anyways, I have a demo, I'm gonna go see if it works right.
CS uses hit group in traceline to determine if a gun hits a shield (maybe). So delete your custom player models will probably solve your problem (you needn't delete custom weapon models)