Yes! Wish I had the same problem. And being I can't achieve better results, I will forgo any advice, and watch for others.

If you're only seeing it now and than...it may be one of 2 things. Your form isn't totally consistant everytime or the arrow's spine aren't consistant from one arrow to the next.

Number each one of your arrows to see if there are certain ones that consistantly give you the nock right flight.

Ray  

Being on the edge of over or under spined will cause exactly that also. What tuning method did you use?....O.L.

Even leaving them full length, and 250 up front those shafts are too stiff even though they show weak once in a while.  I think you'll do much better with 35-55's  

Mike

What OL said, sounds like you are right on the edge, try droping and or raising your brase hight 1/8", it might bring it right in

I would think if he is right on the edge and not getting a consistant reading...his form isn't totally consistant which would explain why some are good and some are not.

If he's that close than that may be as good as he can get unless he first fixes the inconsistantcies in his form.

Or are you guys saying that since he's so close even if his form is consistant he will still get a few arrows that will kick and give different readings than the others?

Whatchya guys think?

Ray  

first things first, your arrows are two stiff. even at full length. go to a 35/55. second, make sure youre not getting any fletching interference, make sure the quills arent hitting the shelf. third, and most important, make sure your release is clean and consistent.