Where do I find this .lua

I searched around on the gmod wiki for a good hour and I can’t find it anywhere. I’m not sure what its called, but the function on the primary attack that makes it do damage to the person getting shot at. I was wondering where this was because I wanted to make a custom weapon for TTT that only kills a specific role. If you could help me locate where this code is id probably get a semi-chub! thank you!!