Re: 900 yd elk?????
For a factory cartridge, 338 RUM.
$$ no option then 338 Lapua.
I wouldnt wish a 300 RUM on anybody.
Long range shooting is a process that ends with a result. Once you start to focus on the result (how bad your last shot was, how big the group is going to be, what your buck will score, what your match score is, what place you are in...) then you loose the capacity to focus on the process.