I agree with bigbulls on this one. I do a lot of testing and playing with a lot of stuff. In my experience if you can shoot well enough to see a difference of 6gr anywhere within 50 yards then you should be shooting for a living and not holding a job.

In my case I often shoot 82gr Nibbs all summer long and change to 75gr broadheads for hunting. There may be a change in impact point but not within at least 35 yards.

Now that you have your scale I suggest that you weigh every component that makes up a completed arrow. I've seen a 7gr spread in the same batch of 4" vanes.