I have a .257 weatherby mag 24" barrel I am shooting 115 vld. I read in the book"hunters guide to long range shooting" you need 1200 lbs of engery for elk and 600lbs for deer. I ran this through my I snipe program after running the numbers I get 500 yards for elk and about 900 for deer. But I also read some where else that the bullet must be moving at least 2000 fps to expand moving my range in to about 600 yards? What is more important speed or engery. P.S. My effective range is about 350-400gun) but each time to the range I am getting more and more but I do not want to waste time or ammo at a range the Bullet will not preform.