Purely anecdotal, as I've never shot an elk. But I have shot plenty of pigs and audad with 30cal bullets.
I'd have no problem with a 165 TTSX or similar mono. I'd not shoot less than a 180 cup and core though. And even at 180, I'd want a pretty tough bullet inside 600.
That said, I shot a number of audad with the green tip Sierra Game King 180s from a 300WBY and they performed much better than expected. Very tough cup and core bullet. If the 165 is constructed the same, I'm sure it would get the job done.
I'd have no problem with a 165 TTSX or similar mono. I'd not shoot less than a 180 cup and core though. And even at 180, I'd want a pretty tough bullet inside 600.
That said, I shot a number of audad with the green tip Sierra Game King 180s from a 300WBY and they performed much better than expected. Very tough cup and core bullet. If the 165 is constructed the same, I'm sure it would get the job done.