At 100yds you really don't need anything heavier then about a 55g. If I remember correctly I can stabilize the 60g V-max and 60g SIE HP, but I cannot stablilze the 64 or 65g bullets from my Contender barrel.
The 55g V-Max and 50g V-Max will drop them with good shot placement.
You will need to use faster burning powders then are generally associated with the .223; I have found that BR2015 works great. There are some other memebers here that have had good luck with blue dot as well.