RE: What premium bullet for elk?
I have used 140 gr failsafe, 160 gr Nosler partition and 160 gr Nosler Accubond to harvest Elk in 7mm rem mag, all worked fine. Try the Federal Premium Nosler Partition or Accubond. If you prefer Winchester ammo you can try the Nosler Partition Gold or the CT Accubond in their supreme line. As far as grain the 140 or 160gr of the Partitons will work but I would stick with the 160gr if you want to use the Accubond's.
Good Luck