Remove the knob from the cocking rod.
Stick two (I think they are 10-32 threads) nuts on where the cocking knob was and tighten them against one another.
Grip the nut closest to the body with a wrench and unscrew the rod.
I actually have the nuts in my toolbox for just such a reason. Vice grips on the rod ruin it and I hate seeing it done that way.
I am unsure what the brass screw is that you are talking about. Valve retaining nut?