pepper mill may not be working right question

[numpty]

Hi
  I built a pepper mill some time ago which, although it works I don't seem to be able to get it overdrive properly, I'm not expecting bags of it as I know it wasn't designed for that. It appears to have a huge amount of gain much more than any other pedal i have constructed. By adjusting the controls i can get a mild crunch if I really hammer the strings (strat middle/ neck - bridge nothing), but I have to have the preset pot maxed out.
The picking dynamics don't seem natural either as there is a big difference in levels between mild and heavy picking.I'm wondering if I need to select a more suitable jfet, is there a simpler way to do this other than the RG way if indeed that is the problem. The only reason I'm asking this is that people appear to rate this design therefore i think there must be something not quite right with my construction