ORIGINAL: fillae
The 340 is actually heavier than the 400. It depends on the spine of the arrow in the end rather than the weight. There are some good threads on this forum about selecting the correct spine. I shoot 62 lbs at 29 in and use the 340's. I used the 400's last year, but switched this year so I could get a little heavier arrow. I use a 125gr head to help get the spine where I need it. With 100gr tips you will be ok with the 400's.
DITTO... Litterally almost to the T. I shoot a 29.5" arrow.. 62#s... and I use the 340s with a 125gr head.
Last year, I shot 400s with a 100gr head and got a weak spine reaction... went to 340s and 125s.... never looking back. Arrows fly beautifully... and at 454 grs moving right at 280 fps.... they are packing a whallop.