BMT's reasons are sound and I believe he speaks from having elk experience as well.

I've hunted elk for as many years as I've hunted game and the 1st 3/4's of it has been with the 180gr. NP's out of a '06 for elk. The 180gr. seems to be the standard and since it falls pretty squarely between the 165 and 200 as the middle choice, it makes even more sense.

The 180's have very effectively taken some 14 or 15 bulls for me. They have never failed me in any way and many other dedicated elk hunters have had the same results. Some might say the 165's, when huntin' deer and not elk, makes more sense. Perhaps, but for one load in that one rifle, I'd rather go just a bit heavier than what I think appropriate for deer, if elk is also on the menu. My '06 loads are all loaded up with the 180 NP's and I'd feel totally comfortable grabbin' it for either deer or elk.

As has been said and is always the right answer, choose the bullet and weight that shoots best for you/your rifle, get a bunch of trigger time behind it......then kill stuff.

Good luck.