You should try some of Precision QT .50 cal on this page. http://www.prbullet.com/pt.htmThey have a twist rate to bullet chart on this site. http://www.prbullet.com/chart.htm Here is a ballistics chart for all the bullets that they make. Study it and make a decision for the best load that you are going for. http://www.prbullet.com/bal.htm you could take any Elk with the .50 QT Polymer Tip Spitzer in 400, 450 and 500 grain bullet- 120 grains powder with no problem. All these bullets work well with a 1in 26” to 1 in 28” twist barrel. This bullet will have devastating effects on thick skinned game.