Whats happening to my arrows at 40 yds?

[Rustywreck]

VS, are you shooting field tips or broadheads?
Are you using a drop away rest?

If you are using a drop away rest, take one arrow and rotate the nock 180 degrees (half turn), on the second arrow turn the nock 360 dergrees, on the third arrow rotate the nock two full turns.
Shoot the arrows in that order and make note of make note of any difference.

If you are not using a drop away, do one full rotation of the nock on the first arrow, two on the second, and three on the third. Shoot them in that order and make note of where they hit.

You may be suprised at the difference a simple thing like nock rotation can make.

There are other things to try, but first give us some of the specs of your bow and arrow: draw weight, draw length, brand of shaft, length of shaft, point weight and fletching size.

Have you tried shooting at 50 yards or longer? I am curious if there is a consistant pattern: 5" right at 45 yards, 10" at 50.