Different bullets for cow elk

[mtnbound]

No, our government thinks they are really quite terrifying…..should be only 80-300 yards

That's unfortunate; the 6CM will be best for rapid follow-up shots. I'm not a fan of the high shoulder as I think it damages more meat than a shot to the vitals, but if you have to drop them right where they stand, check this post out about shot placement. https://rokslide.com/forums/threads/shot-placement-with-223.372844/post-3789226