I don't have a 240 Wby, I have shot a lot of deer, two black bears and a couple bull elk with 100 gr Nosler Partitions in my 6mm Rem 9" twist. Had poor results getting penetration with Sierra and Speer cup and core bullets previously. At 300 yards you won't be giving up a lot to higher BC bullets. Accubonds would also be a great choice.
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