I’ve always heard “5 grains of arrow weight per pound of draw weight.” Sent from my iPhone using Tapatalk
5 grains per pound of draw weight is the standard and what they base the IBO speed of a bow by. So... 350grain arrow at 70lbs... is 350grains. I won't get into why you shouldn't go that light for anything other than 3D shooting.
Not sure what your using it for but for penetration while hunting lighter isn't always better. Sent from my SM-G998U using Bowhunting.com Forums mobile app