I wouldn't choose a 223 for killing elk, but I do believe a 223 loaded up with something like 75gr Swift, 70gr TSX would be at least as good or better than stuff used in days gone by.
Had to be a lot of elk killed with old round ball charcoal burners, 44-40s, etc.
I've never shot an elk but have killed a bunch of deer with .490 round balls and a .223. The .223 consistently inflicts more damage upon a deers innards than the .490 balls.
