I've anchored a couple of semi loads of elk with a .243 never had any trouble finding them, YMMV Rio7
Seems like I remember a post in which you mentioned putting one down with a .22-250. The only reason it stuck with me was that I was wondering if it was the rifle that you bought from me.
Ive shot two of them with a .223
Certainly not my first choice, but I wouldn't balk at a .243 ( Have killed elk with one of those too)