About the Taiwanese fibreglass bow 150#. (Referring geezer measurements: brass 8,89cm draw20,32cm) I am a regular user of those for various experiences.
For my first bullet crossbow (Midleton inspiration)
I used split limb 150# fibreglass
brass 10cm draw 22cm
For the slur-bow (fibreglass)
brass 10cm draw19cm
XIX th cent hunting 2x 150 fibreglass
brasse 10cm draw 23,5 cm
For the bullet crossbow Richard Midleton point out that he don't succeed to use fibreglass limb because of the poor torsion resistance (bullet need extra angle). This is the reason why I used split limb (centre shot, no angle)and there he work pretty well .
I most of the time use the fibreglass over draw. I found a lot of tolerance but by precaution I all-way wrap them with tape string or leaser. When is going to give up it produce crack before.
my bullet crossbow