Killed a bull in 61 last year, glad I took the advice of most on this site. I use the 270gr platinum power belt for deer here in Iowa and they work great, but they do flatten out and break up. Many on the muzz. forum suggested thor so I went with the 300 grain. Smacked that bull right in the t-bone of the shoulder blade, bullet opened perfectly, broke that shoulder and lodged just under the skin behind the off shoulder. Bull staggered 20 yards and collapsed. I don't think a power belt would have done that and glad I didn't have to find out. I'm sure many people have had good luck with power belts, but after my experience with them on deer I just wanted a tougher bullet for elk.