Hello Wanshu,
I have been shooting outdoors this season with 29 3/4" 400's with 110gn piles
and beiter nocks. My findings from lots of bow tuning along with fellow archer moo-mop indicate that 400's are too weak for myself, (I shoot 41# on the fingers) may I suggest you try the tuning method described here:
http://www.archery-interchange.com/f...Park_method%29
This will show you if your arrows are actualy to stiff/weak and allow you to try and match them as best as possible.
All the best,
Alex