Originally Posted by
oneclick
I think those are original, the clamp is counterbored to fit them.
You are likely right - I was really just trying to be funny but my limited experience with the Simplex fronts (probably had less than a dozen in my hands over the years) all had the hex head fixing bolt with the flat screwdriver slot cut in.....
BTW - just another observation on that particular photo - someone really went all in on the tightening anyway - it looks like the delrin has cut into the paint layer. Never had to tighten them THAT much.