...Barnett HiperFlite looks like this:
So, if the cams are going to have stationary axles fixed on the riser, why use composite limbs for spring action and storage of energy? Why not just use a plain steel coil spring in the body of the crossbow?
This will be with a damper, obviously, either a real pneumatic damper, or something like foam padding in between the coil spring segments; a bit like a secondary coil, made of foam, inside the steel coil.
The advantages of a steel coil spring, is that you can have infinite durability, life-span, any amount of force/poundage can be designed into it etc.