I believe the only way to remove the knob is to mill out the round weld that has a star stamping. Of course you would have to weld the screw back to the knob after you remove the pin.
If anyone has a screw that fits in the knob or even the dimensions of the screw let me know. I have a CMP M1D mount that has the screw that has been replaced with a 5/16x28 screw instead of the 5/16x32 screw that is need for the M1D barrel block.