180 grain bullets. These are going to be more solidly constructed than lighter bullets. You want a solidly constructed bullet for the elk. By the way, 300-400 yards is a very, very long shot to make on a big game animal. It is arguable that if you are skilled enough to be taking this kind of shot . . . you wouldn't be here asking this kind of question. No slam of you or your skills intended. I would not be comfortable shooting at a big game animal at 400 yards. Also, most people do not encourage using the .30-06 for elk at 400 yards. I've read a lot of people suggesting that the .30-06 begins to be marginal beyond about 250 yards for elk. Just repeating what I have read.