I have reloaded for elk, 30-06 & 8MM. For the '06 I am using 165 Nosler Partitions (I was able to get blems for a good price), my rifle shoots them very well. I do not know the speed, but I imagine it is faster than 180gr could be pushed. At practicle hunting distances 100-300 yds the 165 give greater kinetic energy than 180gr pills according to the reloading manual ballistic tables. Same concept w/ the 8mm. My 8MM with 150gr gives me greater accuracy and I would suspect greater speed & kinetic energy at expected game encounter distances vs 170 gr.
I have never shot an elk. I have shot plenty of deer & know they tip over easily w/ the above loads and have read that elk are much tougher of course. I would like to know from those w/ real world experience is a lighter bullet going faster (and thusly delivering greater on game energy) better than a heavier bullet going slower and delivering less kinetic energy? On deer the NP push right on through (I have shot them stem to stern and never found one on autopsy). On elk I suppose they may or may not exit, but should do significant damage.
So, then, am I ok going with the 165gr in 30-06 and 150gr in 8mm?
I also have a NP 140gr load for my Swede Mauser that is very accurate and has been chronographed at 2537 fps.
My 30-06 will be my primary gun, the 8MM as a backup in case the scope on the '06 takes a dump on me; the Swede will be in a tertiary role.