the arrows I quoted are different than what you shoot.as you can see I shoot a 400 in the infused carbon and a 500 in the full metal jackets each arrow will act different in you bow.if you have paper tuned and made sure there is no vane contact you may want to try a different arrow.A 340 is a real stiff arrow.there is no reason you should have to shoot a 300. I shoot a monster XLR8 rated at 375 IBO 28'' draw at 70lbs shooting now at 334fps with the arrows quoted and I have no problems.no one should have to go stiffer than that.mabe try to paper tune at 15 to twenty yard to.also if you have different colored vanes your arrow will look as if it is flexing or wobbling. paper does not lie.