what calibers would you consider to be adequate for elk, and what range? contender, encore?

how about the 375jdj? what's it's practical limit? is it's trajectory flat enough?

375jdj, or 338jdj?(contender)
300win mag,or 338win mag?(encore)

Kentucky has a growing elk herd, and a man just never knows what the future holds. would you feel comfortable with the 15" 7-08?

lot's of questions, sorry just lookin for ideas