340 is the spine recommended, however, if you can get a heavier stiffer arrow to fly good it will perform better under all conditions. Kinetic energy is measured at the bow. A stiffer heavier arrow will have more down range penetration and kinetic energy. I shoot long distance field. A 120 gr tip flies flatter and has better control in the wind than a 100 gr tip at 100 yds. A slower controllable arrow in the middle beats a fast arrow in the dirt every time.