300 grain for an inline muzzleloader bullet. I just don't know if a jacketed pistol bullet will less grains could knock down an elk. I guess a person would have to chrono them and find out. Anything less than 1000 fpe I would have doubt killing any elk quick. It may kill one, just not quick. And if you want to track for ever and a day. I just dont know. Last hunting season my 300 grain XTP bullets knocked everything down and the went less than 25 yards. EXECPT for one stupied doe deer. It was a double lung shot and she went 200 yards, almost lost her. So...what does that tell you? Probably nothing, sometimes its just a fluke. Just gotta shoot what your confident in and do testing. I"ve always liked the frozen milk jug. Figure if a bullet can make it crushed ice and pass through it would be fine on large game. I plan on Chorono the 300 grain XTPS this summer. So i will report that when I do it.