PSE recommends that you shoot at least 6 grains of arrow weight for every pound of your bow. Hence, the 70 lb bow is 420 grains. They also know people shoot IBO tourneys and shoot 5 grains per pound. They will still warranty your bow but DO NOT shoot under 5 gr/lb. It is like your car, if you unnecessarily rev your motor up at stop signs, your engine won't last as long. If you don't keep revving it up and drive it a little slower, your engine should last longer. No senseless wear and tear on it. Youre bow is the same way. I personally like about 5.5 gr/lb to about 6 gr/lb. Makes the bow a little quieter than if I shoot 5 gr/lb.