I tried the prod on the tiller and it was just over 100#, but I probably didn't get it quite back to full draw, I didn't want to risk over-straining it. I plucked up courage and had half a dozen test shots and then tried it 3 times through the chrono' (with the heavier commercial bolts), average was about a disappointing 170fps. I then tried the old prod with patched and repaired belly, using the same bolts of course and it was about 5fps faster!
The new prod took a hint of set so that it needed very little flexing to get the string on. The old prod required a little more flexing despite being about 2 " shorter.
My conclusion is that the Yew is a better belly than the bamboo... of course this may only apply to this particular yew and this particular boo (I don't think it's Tonkin boo, which is considered to be the best).
It also illustrates the dilemma of crossbows, trying to get decent performance from a manageable short prod whilst maximising the draw length, without resorting to bolts that are really too light and risk damaging the prod.
I've added a pic, showing brace and drawn superimposed so I can see how it flexes.
I'll probably re-visit this at some time, and if I can get up to 200fps I'll invest in a scope and try it at a field shoot. It's not that much faster than a good primitive at the mo', after all Twister has been clocked at 166fps (prob' a bit slower these days).
One of the Guys on Facebook was suggesting heat treating the inner faces of the boo, but if you've been following this project you'll realise I've gone through enough experiments for now!
Any how onwards and upwards onto my next project which is...