Whatever bullet shoots best out of your gun and gives the most repeatable accuracy. Make sure you shoot at 300 and if possible beyond that for grouping. Nosler partiton,Swift a frame, CT failsafe are bullets I have used before with good results. Have not used accubonds so I can't comment on them. Federal seems to have a wider selection of really good elk ammo then the other manufacturers but try them all. Not sure if anyone has used corelockt ultras I have in 7 mag 140 grainers and they shoot beautifully and really do the number on deer..elk is a horse of a different color though.