i have experienced the bow holding more reflex if it is heated into shape before putting the sinew on(then bracing backwards to cure),, also a course of sinew means something different to everyone,, so I have weighed my sinew so if it is not enough I can put more etc,, I have had good results with about 800 to 1000 grains of sinew applied to 50ish inch bows,,less than that and seems the bow does not hold reflex as well,, still shoots well but not quite the cast you would like,,,