Bluefeather's advice is good, for a 70 pound bow. IMO, as draw weight and kinetic energy decreases, grains per pound should INCREASE. You have to offset the KE loss with an increase in momentum to ensure adequate penetration. The light arrow/high speed/high KE theory works for only one reason... They are driving those light arrows out of high performance, high poundage bows fast enough to generate a heavy dose of momentum. For example, a 350 grain arrow weighs half as much as a 700 grain arrow. It has to be traveling twice as fast and carrying twice the KE to equal the momentum of the 700 grain arrow. Or, to say it another way, it has to be traveling twice as fast and with twice the KE in order to equal the penetration potential of a 700 grain arrow, all else being equal.

So, when you shoot a bow that simply won't generate those high speeds and high KE numbers, you have to get your momentum the old fashioned way, by using proportionally heavier arrows.

As for trajectory, when you're talking about hunting whitetail deer where the national average shot distance is less than 23 yards, then trajectory is a non-issue.

So, ghillie, I think you've got a fine arrow for hunting. You might want to go to a lighter one for shooting 3D, where the targets are often at longer distances than you'll ever shoot while hunting.