How do I make a gun like turbofusion's?

I wonder how I would make a gun like turbofusion's. I wonder where would you get information on how to make a gun like his. I have made a gun with simple raycasting but nothing like he does. When I try to look at his scripts they are just too complicated for me to read. So does anyone know any videos or wikipages that will teach someone how to write scripts like turbofusion?