Pending on what bow...hard cam ...soft cam etc...and your exact weight of bow...
with what you specified
If bow is 65 LB or under...than the .400's will be ok ...on the light side
If bow is 65 LB or over ...than I suggest the .340's
Either under or over 65 LB you can use the .340's as most bowhunters prefer a heavier arrow...
Whereas the .400 will be under spined the higher you go over that 65LB mark
Neil