question about hunting with stone point

[rappstar]

so i've got my bow bare shaft tuned (I'm pretty sure).  Any variances at this point are slight and I'm sure they are due to form.

i have the 65#-70# cedars cut to 30 inches with 125 grain points.  

now my obsidians are around 90-110 grains.  i don't want to "practice" with them...just hunt.

is there a standard best practice on how i should calculate the arrow length for the ones i will mount the obsidians on?  in other words, how much should i lengthen from my known config that works.  Ex. 1/2 inch per 10 grains....

maybe i am over thinking this and it really doesn't matter.

[Pat B]

I believe spine weight is estimated at 28". For every inch above 28" arrow, subtract 5# of spine weight and for every inch less than 28 add 5#. This is with a 125gr head.
  I would never hunt with an arrow I hadn't shot and was satisfied with its flight. Too many variables.   Pat

[dino]

You should practice with them atleast a few times.  Use some loose straw bales to practice into.  You don't want to be suprised at their flight when your in the field. dino

[Keenan]

You can also shoot them into the thick white styrofoam targets that wallmart sells for $15.00 I use them alot for practice with stone points.I agree with Dino you need to know how they fly.Keenan